Married men will tell you how ill-mannered their wives are, how badly they treat them, and how they make the marriage and home unbearable.
All that blah-blah-blah (whether true or not) is just to gain your empathy and to sleep with you.
You have no business being a safe place for a married man. If his wife is genuinely intolerable, he should seek counseling and/or divorce her.
Until then, don’t be fooled!