Well im not going to create a male version of this topic so ill just post this here.
My personal advice is to kick him to the curb. If he's paying more attention to the computer than to you what is in the relationship for you?
Especially now that you want to confide in him/talk to him.
Is it possible that he's cheating on you? You'll often see people getting very distant when they're cheating.
Being together 3+ years I understand that it can be hard to leave, to start over, what have you. But clearly he's not there for you anymore. Plus according to your profile page you're 17. I'm not going to say "that's too young to have a serious relationship" my wife & I started dating when we were 16, and have been together almost 8 years now, married for 2. But it's not like you'll have to worry about being alone forever.
Personally I don't care if you're 65, if you're not happy get out. What's the point of staying with someone if you're not happy.
At least sit him down, face to face and say "listen or it's over" then pour your heart out. If he's still bull shitting you then get out of the relationship before it gets worse.