<human>: Can you summarize the given text in a few sentences?

My girlfriend and I have been dating for a little over two years. We both love each other very much and talk about moving in together after we graduate from the college we both go to.

Our sex life has declined over the past year or so, and after several talks about it, these are her feelings on the issue:

• Whenever we're together and she declines sex because she's tired or just not feeling up to it, I get disappointed.

• The way I choose to express my disappointment essentially ruins the rest of the time we spend together; essentially, if we're having a good time, I kill the mood.

• It's gotten to the point where this is something she thinks about whenever we're together, which kills her sex drive entirely, and has led to the decline in our sex life that we've been experiencing.

**She's totally right.** I do get disappointed, and pissy and angry, and I do kill the mood. This is something I need to fix, because I love her and I don't want to put her through that, and because I don't want to be that kind of person. I need to make a mental adjustment, which can be difficult for me.

Basically, if anyone has any advice, I'd love to hear it. We're on winter break right now and we're in different states, so we're hoping that the time apart will help things somewhat, but I want to take control of my side of things.
<bot>: I'm disappointed when we don't have sex and it's ruining things for my girlfriend. I need to change. Help?