A cancer diagnosis can expose cracks in a marriage that were already there — or create new challenges even the strongest couples aren't equipped to navigate. While the reasons any relationship ends are deeply personal and often impossible to reduce to a single cause, research has found that divorce is significantly more common when the woman in a heterosexual marriage is diagnosed with a serious illness. One 2009 study found that among couples who divorced or separated when one partner became ill, the risk of divorce was as much as six times higher when the woman was the patient.
Of course, without knowing the health of the relationship before the cancer diagnosis, we cannot conclude causation. "The research isn't saying cancer caused the divorce, just that there's a relationship there," says licensed professional counselor and certified sex therapist Tiffini Sharifi. She says cancer often magnifies problematic relationship patterns that already exist.
At the same time, cancer might also empower a woman to leave a partner that is unable to support them through sickness in the way that they need.
No one understands that better than 61-year-old Heather.
When Heather met her now ex-husband at a coffee shop, she thought she'd found the perfect partner. Both had children from previous marriages, their families blended naturally, and she admired his military career, despite the frequent overseas deployments. "He was the 'big deal' in our family," Heather recalls. "The hero. We were all so proud of him."
Then after a routine mammogram, doctors called Heather back for additional imaging. Because communication during deployment was difficult, the couple devised a code: Heather would text him a “1” if everything was fine, a “2” if the results were inconclusive, and a “3” if she had cancer. A few days later, she sent the “3”.
Heather would need a double mastectomy, followed by chemotherapy. "It was hard saying goodbye to my breasts," she says. "It was an amputation."
One study comparing the self-esteem levels of breast cancer survivors who had undergone a mastectomy against a group who had never had breast cancer found a significant statistical difference, with the mastectomy group reporting their self-esteem to be much lower.
Sharifi explains that this makes honest conversations about physical and emotional intimacy especially important. Intimacy issues can also be intertwined with a changing sense of self-image — particularly for women who have gotten mastectomies.
Heather’s then-husband flew home for her surgery, but soon after he returned overseas. As Heather focused on getting through treatment and caring for their four children, she barely noticed how much her husband had withdrawn. "The doctor offered to video call him into appointments," she recalls. "But there was always an excuse. He couldn't physically be there, but he also didn't want to participate emotionally. Looking back, he made that very clear. I just didn't pick up on the cues."
As treatment continued, Heather noticed her husband becoming increasingly distant. Eventually, she learned he had been unfaithful after her diagnosis. "He had multiple affairs," she says. "One of the women ended up reaching out to me." At the time, she couldn't help wondering whether the changes cancer had made to her body had played a role.
Sharifi says serious illness can make existing relationship problems impossible to ignore. "If there were already issues with sharing responsibilities or a partner who struggles with empathy," she says, "those things don't disappear during treatment. They often become more obvious."
When one partner struggles to provide emotional support during a couple’s first real confrontation with grief or uncertainty, it can be easy for the other person to wonder whether they’ve done something wrong. In reality, it may actually be an indication of that person’s capacity for empathy in general. The way someone shows up for a loved one in crisis often reflects their broader understanding of communication, connection, and recognizing what another person needs. For Heather, her cancer diagnosis did not cause her then-husband to distance himself: It may simply have brought an existing dynamic into focus for the first time.
The emotional distance Heather felt with her then-husband extended far beyond physical intimacy. Between chemotherapy, raising four children, and simply trying to survive, she wasn't paying attention to what was happening in her marriage. "My focus was just getting through treatment, and continuing to raise our kids with as little stress as possible," she says.
Instead of clocking his absence, Heather noticed the people around her who quietly stepped in. "My mom helped a great deal with the kids, and my sister became the coordinator who made sure everything got done," Heather says. "And then my best friend would just come and sit with me. Even if we didn't talk, I felt calmer just because she was there."
One moment, though, has stayed with her more than any other. After chemotherapy, Heather was at work when a sudden hot flash — a side effect some women experience with treatment — hit her during a meeting. "I was so hot I think I turned purple," she remembers. "A gentleman at the table stood up, got me a glass of ice water, and just quietly put it in front of me. Something about that small act of kindness — I melted into a million pieces."
Although Heather knew about her husband’s affairs, she remained in the marriage for another two years after treatment ended. "I didn't want to be divorced again," she says. "I didn't want to put our kids through that."
Eventually, after the children had grown and left home, Heather made the decision she had been avoiding. "I knew that if I wanted to maintain any of my self-respect, I needed to leave him," she says. "I needed to put my health and my happiness first."
Looking back now, Heather doesn't believe breast cancer destroyed her marriage. "Breast cancer didn't cause my husband to act like this," she says. "It was just who he was." Instead, she believes the diagnosis forced her to confront truths she'd spent years overlooking. "Our life together had always centered on him and his needs. I was the one who held everything together. This was the first time he really needed to show up for me, and he couldn't."
Sharifi says one of the biggest warning signs of divorce isn't conflict itself — it's how a couple fights. "Decades of research by Drs. John and Julie Gottman point to four communication patterns that can be lethal to a relationship: criticism, contempt, defensiveness, and stonewalling," explains Sharifi. "These patterns often intensify under the added strain of a cancer diagnosis."
She encourages couples to check in with one another regularly throughout cancer treatment — not just about appointments and logistics, but about how each person is coping. Those conversations can be difficult, but they also create opportunities for connection during one of the most stressful experiences a couple can face.
While the divorce process was painful, Heather no longer sees it as the tragedy she once thought it would be. "In some ways," she says, "I think breast cancer saved my life."
She doesn’t believe her diagnosis changed her husband as a person. It simply revealed what she'd been unwilling — or unable — to see. "I got to see who he really was," Heather says, "and that wasn't the person I wanted to grow old with."
Today, Heather lives on her own, a life she says she genuinely loves. Despite the end of her marriage, she remains grateful for the years she spent helping raise his two children alongside her own. "That was the honor of my life," she says.
If there's one lesson she hopes other women take from her experience, it's that surviving cancer shouldn't mean ignoring your own emotional needs. "Don't lie to yourself," she says. "And don't try to be brave all the time."
Cancer demands extraordinary strength, but it also reveals who's willing to stand beside you when you're at your most vulnerable. Whether that support comes from a spouse, a sibling, a friend, or even a stranger offering a glass of ice water, Heather believes it's worth recognizing — and accepting.
