Why do I get so jealous seeing pictures of my boyfriend with other girls from years ago?

[Brooke]

My boyfriend and I have been dating for almost 4 months, and we're both really in love with each other. We trust each other with everything, he's my best friend, and he is one of the best things I've had happen to me.

I've had kind of a rough past with past guys I've dated and it's really hard for me to let my guard down and completely give my heart to anyone. But he makes it easy.

I guess I may have trust issues from past relationships and I'm naturally a jealous person anyway. But anyways, today I was going down my FB timeline and I saw pictures of my boyfriend tagged in some girl's album from a year ago at some award ceremony they went to for getting some scholarship. It was only him, her, and some other girl. He and I didn't even know each other then, so I don't know why I'm getting so jealous but seeing them in pictures together made me want to cry.

The girl was really pretty and I figured maybe it was someone he went to church or high school or something with. And I'm sure there was or never has been anything going on between them. But it just kind of hurt my feelings seeing them in pictures together.

I don't want to ask him about her because I don't want him to get the idea that I'm some controlling, clingy, crazy girlfriend (which I'm not!)

Is there a psychological reason why I got jealous? I don't know why! Because I'm sure that I'm just as attractive as she is so I don't know why I'd get so envious! Can anyone help me? Thanks!