I'm going to accept blowjobs from a gay friend and then cancel our plans for later.
Why are you going to cancel?
Because I have a boyfriend.
Cancelling on plans you made with someone is rude to the person who set time aside to spend with you. More importantly, does your boyfriend know you are getting action on the side?
He doesn't care. he knows I would cheat whenever I have the chance.
Taking a blowjob from your friend with no concern for reciprocating by spending time with them is just using them for your own purposes and it's inconsiderate. Don't accept sexual favors when you don't care about the other person.