Hello Geminis

First I'd like to introduce myself. I'm a Capricorn, ascendent Gemini. My mother is a June Gemini, and my 3 very close friends are June Gemini. I love them, respect them for who they truly are and I get along well with them.

However, as the rational Capricorn that I am, I'd like to understand a few things about them that I have yet to figure out.

My 3 Gems close friends are attracted to possessive women. They come to me, complain about being unhappy and trapped they feel.

One of them stayed with a Pisces for 2 years, she lied to him about going on the pill in order to have kids with him. Now he's "stuck" (stuck, being his word) with two kids. He also want to win her back. He cheated on her, and they've been separated for two years. He told me he doesn't like a lot of the things she does, but can't live without her.
I don't get it.

This same Gemini and I have been close for 8 years. Now, I'm sure this will sound weird to many, but I respect his flirting, his liberty, his dreams, and I've always tried to guide him in the right direction.
Right direction being not being in abusive relationships (There's been more than one. A girl who cheated on him 3 times and he stayed with her anyway) I try to show that it's possible to be loved without being screwed. Yet, he wants to go back to the girl who made is life miserable. We talked about being together. He told me he loves me many times, and I believe him. But he also talk about this girl.
She's in an happy relationship now. Don't want Gemini back, but he's ready to fight.
I'd like to understand.

Also, about this same Gemini. He's very possessive with me. He says I'm his, calls me his wife even though we're not married.
We've been intimate for years (But not when he was with that crazy Pisces) and sex wise, we're like a perfect match. He's a freak, I'm a freak. It's perfect. Even though we're not in a relationship, it's like we are.
He always wanna know where I am, what I'm doing, with whom, etc.
And if I ignore his texts or calls, he gets mad.

But when I'm the one asking things like: Hey where are you? He doesn't answer. There's a little "r" next to iMessage, saying he read, but doesn't answer.
So I try to get his attention, like he always do with me and no answer.
I learned to deal with it, but I'd still like to understand.
I know Gems are known to flirt and cheat, but I know he's not seeing other woman.
Flirting yes, but it's who he is, so I let him do his thing.

Is this