Questions: Marriage & Weddings

My husband and I have been together for 12 years; since he was 21 and I was 19. We started out as best friends and within 6 months we were living together and in a serious relationship (the first and only serious one in my whole life). We used to be so close and now I feel like I'm just here to cook, clean, take care of the kids, and have sex with him whenever he wants it. I've told him that I feel like he doesn't care about me anymore and he just gets angry and treats me like a bitch for telling him how I feel. He has a life outside of the home; work, friends etc. I have nothing. I have no friends and my life revolves around being a homemaker. Any time I try to make friends he automatically hates them and then I am treated like a fool because they don't meet his standards. I have no family within 300 miles and anytime someone comes to visit he acts like he wants them gone as soon as they get here. He treats them horrible (disrespectful and rude) and I've always been friendly with his friends (even the ones I really don't like).
I feel like this relationship is a joke sometimes. Like people are looking at me like I'm an idiot for staying with him. When we fight (which is rare actually) he always says he'll try harder but the next day it's like nothing ever happened and things go back to the way they were. He expects me to do whatever he wants (and yeah I do it) but he can't even listen to me when I ask him to bring home milk and bread from the store. It can even be something extremely important and it's like he won't listen for even five minutes. He forgets stuff as soon as I'm done talking to him. I feel unloved and VERY unappreciated and he doesn't give a crap. He says he does but he keeps doing the same thing over and over again. I've even thought about leaving him because I feel like more of a maid/nanny than his wife. But he's also very jealous and possessive of me; said once he'd shoot me if I tried to leave him. I don't know what to do. I feel trapped and very alone

I've been seeing a lot of questions on here regarding men and marriage, so basically my question is if you're a man and don't wanna get married what are your reasons behind this? And why do you feel like some marriages don't work out?

*This is not to all men just the ones who don't wanna be married.