Men like to claim that all they want in a partner is "don't be fat" and "don't be a bitch".

This is, however, clearly false.

If these men want kids, they assume that any woman they get with will be a capable and willing mother. They will not look for red or green flags from which to assess her capabilities at actually rearing offspring. They will assume that she can do it (and is will be willing to with enough manipulation convincing) just because she's a woman, and then wonder why she leaves when that's not the case.

If these men want a clean house, they assume that any woman they get with will be capable and willing to do the bulk of the domestic labor. Toilet stinks? "Eh, she'll do it when it's bad enough". Dirty dishes? "Eh, she'll do it when she's tired of seeing the sink full." They don't look for the type of woman that actually likes doing the housework. They assume that any woman that gets will them will be happy to do all the "woman chores", and then wonder why she leaves when that's not the case.

If these men want to live in a certain type of area (urban, suburban, etc...), they assume that any woman they get will be happy and willing to drop her dreams of an ideal lifestyle for theirs. They don't think about how these differences could be irreconcilable incompatibilities. They just assume any woman they get with will bow to their will, and then wonder why she leaves when that's not the case.

Men have desires for what they want in a relationship, but they assume those desires will all come to be regardless of which woman they get with. As far as they're concerned all women are interchangeable for what they provide to a relationship. So they don't actually look for the women who are compatible with what they want. And then they wonder why their relationships don't work out.