Just Cant Get Enough

I have been in a relationship for the past five years, i have had all my sexual experience with this person. I went away to college for 3 out of the 5 years and now things have changed. Now that i have more time for him, its as though he doesnt have time for me.
I feel a bit ashamed because i am ADDICTED to sex. When i go more than a week without having sex i am at my worst, i can function properly and easy angered and i am mean to the persons around me. I think he has an idea that i love love love sex but because he is a bit older than me he will say he is tired after round two. This is driving me crazy because i am considerate enough to give him a break when he needs it!!!!!!!!!!!!!!!!! Sometimes i must admit that i have been more than tempted to get with someone else but in the back of my mind there is always guilt.