What's wrong with me

Right I know this is for gay related problems and I am bisexual but I've ended up with a guy and I'm not used to relationships and need help!

It's been 3 months, I'm 18 and he's 24, but he doesn't make me happy at the moment, everything I say he has something negative to say about it or says I'm wrong for example- ill say something like Lily's are poisonous, and he says no there not its not gonna Killy you. Another example- watching a film and a guy murders a different woman every night and has got away with it for 10 year I comment saying you think they'd be on to him by now, and he argues saying no they wouldn't and list a load of reasons why he's right.

At first It never bothered me too much but resently I just can't be bothered with talking at all cause I know at some point what I say is going to be wrong. And when I do and he does do it I just go silent and into a kind of mood. I know I'm doing it but can't help it, it just really gets to me and makes me unhappy, so now he's always asking me what's Wrog what's sup am I going off him why arnt I still attracted to him anymore, and I just say no I'm fine, because I don't want to start and argument and if I was to tell him what's wrong he'll only disagree with me, I find my self alwaysw in this mood now and it's effecting us a lot I don't want sex cause I'm down, I don't wanna talk, go out or anything.

But I don't want to split up with him, I find it hard to get a boyfriend and I don't like been alone I don't want to split up with him.

Also he's really not romantic at all? Like seriously no romance at all he's never done anything that I could say ahww yeah that time he did this. He's 24 year old he know what girls like, and you would think if he knows there's somthing up with me and say I was going off him he would try harder and do somthing sweet instead he's distancing himself.

And I'm getting clingyer and jealous, I'm mardy when his around but jealous of who he's with when I'm not there