I know that nobody will agree with me here, but I do think that that is exactly what men want. Watch ducks chase each other round the park. The males are driven by the need to have sex. The females are driven by the need to reproduce and nest. So the women generally (not always and certainly not me) want cosiness and marriage, the men know they have to agree to marriage if they are going to get sex regularly. However, these days, as Sqad says, marriage is not popular anymore. In the olden days men had to date, work hard at wooing, propose, show that they could support their lady by providing security with a home that they could raise children in, whilst he worked. Since women have agreed to have sex without marriage, men are not tied to any agreement, and so now expect sex with a new partner, with no promise of anything more than sex. Not all men of course, but that is now the culture we have; men go on dates to have sex. They have skipped all the stuff that we used to have leading up to commitment, and now just get the bit they are genetically programmed to want. This leaves women either putting out and then feeling lonely, or not putting out and staying single. And yes, not all, but a lot! Read Pride and Prejudice if you want to see how relationships used to operate compared with now.