If men rarely take back cheaters, where are these simps coming from?

My friend cheated on her boyfriend twice and he still took her back. She's supposedly remorseful this time and he gave in.

Then this apparently happy married couple in my area seemed too good to be true. The darkest secret is that she had an affair long ago and 2 out of their 3 children aren't his. He knows it, they went to counseling and still stayed with her, still raised them.

It makes me wonder what exactly do these girls have that makes those simps want to stay with them? Where are simps like that coming from?
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+1 y
Is their self-esteem that low to the point they will just accept any woman that wants them? My friend clearly doesn't love her boyfriend. Then in the 2nd chance, that should've been a divorce.
If men rarely take back cheaters, where are these simps coming from?
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