This is my first time posting on a forum like this and it is a last ditch attempt to sort out the way I act. I' am 19 years old and I have only been in 2 relationships my entire life.

In my previous relationship I was incredibly insecure, and added to multiple things it eventually led to the relationships downfall. I was not exactly treated right by the girl, she'd lie and talk to other guys without me knowing, and I think this is what caused my insecurity to flare up. A while later I went into a relationship with a much nicer girl, she is loyal, kind, and loves me, which I should be certain of because deep down I know its true.. except there's a part of me that keeps nagging at me, telling me it isn't.

She has never done anything to betray my trust, she has never done anything to hurt me and I'am incredibly lucky to have her, but sometimes I get my mind wrapped around the smallest things and its almost as if I make them into a much larger deal than they should be. For example, I keep telling myself that if I don't interest her constantly, she will be interested elsewhere and leave me, just like that. I convince myself I have to be perfect to make sure she'll be with me, I compare myself to everyone, thinking of how I can improve.

There is times I see sense and realize, if I wasn't what she wanted she wouldn't be with me, but for some reason I always become insecure again at some point. It usually builds up inside of me, I talk to her about it and it ends in an argument. Its like a blowout for all my insecurity and afterwards I'am okay for a while. I can tell it hurts her a lot, she says she has done nothing to make me think like this, and it hurts me in turn because I know its true and I know i'm insecure... yet I cannot stop my insecurity creeping back.
As I said its my first time posting here, I'm upset by my actions and my state of mind, I don't want to drive her away because I love her an incredible amount. If any of you have any tips or personal experience I would be grateful.

Thanks