If I take a step back, and examine the situation from a third person point of view, it seems that he has just found a new friend, and they are just getting to know each other. That's why it seems like maybe he is more affectionate with her atm than with me. We had our honeymoon phase, and was like that too. (well we were all over each other lol) So I guess it's just that it's something new, they are just exploring each other, getting to know what makes each other tick.
Also, come to think of it, when we are at her house, I am just fine, because usually, they are playing video games, or up in her room talking, while I'm occupied with talking to her mom. (I was surprised at this, but me and her mom are getting to be, like, friends!) I don't even think about what they are up to.
But when she was here, I couldn't stand being in the room with them, whispering to each other, being lovey on each other. So I went into my computer room, and just cried. It was also like, she was invading on my territory? (I know she didn't mean to, it's just how I felt.)
Also I might want to add, me and my bf have Asperger's. I think because of this I usually have problems understanding my emotions. When I first started feeling jealous, I didn't understand it. I felt a tightness in my chest, I felt a little sick to my stomach, my heart was going a mile a minute. And before I could figure it out, I was crying. So my conclusion is that what I was feeling is jealousy.