Do you have a girl friend or just know someone who says this line "I can't leave him because of the kids" ?

I have this friend, she's married. Her husband is cheating, and has cheated over and over again, when we talk I always tell her, you could leave, you know? Every time this topic comes up, she always respond that she could not leave because it would devastate her children (her children are aged 20 and 14) and it would damage them and would be really hard for them to deal with.

Do you believe in this line? What about her, though? Doesn't she deserve to be happy too? Is it true that her children won't be able to handle it?

She cries to me almost every time we see each other, and I'm so tired of hearing her pain because she just says the same thing over and over again, but she's my friend and I want to be there for her at the same time. What do you guys think?

Should she leave or not?