The reason they are more likely to be caregivers in a relationship is because they remain healthier longer.
On an interesting note, long before I heard about MGTOW, I discovered a subset of women going their own way. I couldn't understand why all of the older women I knew at church refused to get married again or be in a relationship after their husband died. Especially since there were quite a few available lonely widowers who did want this. Finally one woman told me, "We don't want to spend years being a caretaker again." It's an interesting twist. Older women have been "going their own way" for generations with no social backlash.
It's also interesting how the typical greater social isolation of men after death of a spouse or divorce plays into medical issues, when the assumption is always that a woman will be the caretaker. I recently was the designated driver for an older (mid 50's) male friend having same day surgery. The receptionist asked him who his emergency contact was, he hesitated, and then gave the name of his ex-spouse. Not his brothers or many male friends. I quickly substituted my name, to his relief, but I was stunned that clearly he felt he needed a female for this category. Then the doctor comes out after surgery, calls me into a private room, and gives me a detailed report of the surgery, prognosis and the home care I needed to provide. I couldn't think of any tactful way to tell this doctor, "I'm not his wife, I am just his neighbor." I was there, I was female, well obviously in this doctor's mind I was going to be providing home care and should know all the details of the surgery.
I sat in the waiting room of a very busy out-patient surgery practice for close to 6 hours. Not a single male patient walked in without a female by his side. (Designated drivers are mandatory.) SO's, mothers, sisters, female friends, but not fathers, brothers and male friends. It's a really silent prejudice in America. If you are male and sick, then you better be able to produce a female willing to take care of you, or people will think there is something wrong with you.