heavensent,
I have had experience with both sides of your situation. My exgirlfriend tried to initiate sex with me but I turned her down because I didn't love or want her anymore which is different from your situation. I wouldn't worry about one night to much he might have been tired.
Now I am married and my wife never initiates sex and I am turned down so much it is driving us apart. We have had sex 3 times since August. I just thought I would share some of my experiences.
Your boyfriend is a LUCKY guy. You please him even if your tired or not. I would love my wife to just please me somehow even if she is to tired or not.