OK, I am ready to explain what is generally wrong with her post.

So I just spent some time with my current partner (in an open relationship) and he told me that a while ago he had an internet dating profile and he was intentionally looking for married women.

His reason - he did not want to face a "surprise pregnancy" by a woman who would engage in unfair tactics in making him marry her. Something like this happened in the past, so he wanted to be protected. Eventually, though, he met a woman who was not married but was on AD's and not wanting to get pregnant because of AD's being teratogenic. That was good enough for him; he had a fairly long-term r/s with her which lasted until she met somebody who wanted her to move in with her. My current partner, when he was her boyfriend, did not want her to move in. She told him that she loved him, but was unhappy that he would not move in with her, and moved in with another guy as soon as she found somebody who wanted to move in with her, and my current partner was upset because she used to tell him that she loved him, so, in his mind, "how come she quit so easily if she loved me?"

To which I tell him - she did love you, I am sure, but she loved the idea of moving in with a boyfriend MORE than she loved you. She still loved you, but she loved the idea even more. He seems to be happy with this approach of mine.

Anyway, his initial desire to have a relationship with a married woman who would have him on the side was motivated by a very specific need to make triple sure that he would not have more children (he has 4 and he really cannot afford more). Condoms alone are not foolproof - he also needed the woman herself to be motivated to avoid conception.

So here is one usecase.

There might be a myriad other usecases.

A woman may want to date a married man because she wants a part-time relationship with no strings attached. Or, because she is unsure of what to do in the long run, and does not want a relationship that can gets serious enough soon enough until she figures things out. Or, for many other reasons.

The mistake made by the woman who posted on Craigslist is that she assumed that every other woman on earth is like her in that she would want to be married to that precious specimen that is her husband. Not true. Very much not true. Not every woman wants to be married to her precious husband - most do not.