Here is the problem:
In the modern sense of the word "relationship", there is a phantom hyphenated prefix that is almost always left out. The prefix is "Sexual-". And in a Sexual-relationship, if the sex is removed, the relationship is hollowed out.
The thing is.. folks have rationalized their sexual relationships into more than what they are. It's really just sex. And all the other stuff is to facilitate the sex. And if you don't think so, just stop the sex and see what happens to the so-called "relationship".
Truth is.. the word relationship doesn't mean anything without some context. And if sex is the main point, then sex is the key to holding it together.
And the same goes for other types of relationships. There are men and women whose relationship is based on children. And so the phantom hyphenated prefix for their relationship is "Parental". and that's why you'll hear folks saying, "I stayed for the kids". Take away those kids, and that relationship falls apart.
And there are two-sided relationships where one side is based on one thing.. and the other side.. another thing. Sex and Money are a familiar pair. He's with her for sex... she's with him for money.. or vice versa. His money dries up and she's audi.. her sex dries up and he's audi.. that is.. unless they have some other "relationship" between them that is strong enough to keep them together.. like a Parental-relationship.. or a Professional-relationship.. or an emotional-relationship.. in which case, they may each find other ways to satisfy the needs that are no longer being met through their relationship.
For example.. If she needs tenderness and you are no longer tender, she will either pout or find some way to compensate. like hating you.. or leaving you.. or hurting you the way she hurts... or maybe she'll recognize that most guys are tender in the beginning.. and so she'll continually search for beginnings.. where he's tender and attentive.. and when that phase passes, she bounces on to the next one.. trading her sex for his temporary tenderness.
Here is the problem: