Can someone explain this to me please?

Ok....so my friend just broke up with her boyfriend 'cause he was being dumb. He hurt her pretty bad, he basically cheated on her and she wants him back! I don't understand it. And she says she needs him and she misses him. I tried to tell her that she doesn't need him. She doesn't need him to make her happy and she doesn't need him to make her feel good about herself. and shes saying some bullshit about how she needs him to sleep at night and blah blah blah. I don't know how she needs him to sleep at night...they never spent the night with each other. Am I being insensitive? I don't understand how us girls work. I mean if i learned anything from being single my whole life its that I don't need a guy to make me feel good or be happy. I mean sure, it may be nice to have a guy in your life, but i don't think have a significant other is a necessity in life. And obviously when you're single you have days where you feel shit-tastic about yourself (trust me i have those days). But obviously i don't know anything 'cause she keeps feeding me a bunch of cliche bullshit that i just don't understand. May i am being insensitive..but could someone explain to me why the hell girls want guys back after they hurt them, and why they think they NEED this guy in their life? IT just really pisses me off....but whatever -.- rant over