OP - Boyfriend was understandably embarrassed about being found masterbating. Then he tried and turn it around and somehow put some of the “blame” on you - And that’s just stupid. Humans practice “self gratification”. It’s one of those private things most men and women do. It’s not cheating or infidelity. It’s supposed to be private, but some people are careless or just plain dumb and they get caught. Then they are embarrassed.... OP, I don’t think this is a serious issue by itself unless you or boyfriend choose to make it so. On the other hand, if boyfriend is always at home jerking off instead of working or looking for a job that a problem. Or if boyfriend has a habit of trying to make out that girlfriend is at fault for everything that happens then that’s a problem. Or if OP cannot deal with the concept that boyfriend is human and practices self-gratification (discretely and at appropriate times) then that’s a problem.

Sometimes I just want to fly solo. Having someone interrupt is a mood killer.

Don't you mean cumming home? I'll leave

Fix the mood by finishing it for him?

Is he shy and a little overweight?

You should have said "THAT'S NOT RIGHT! Let me show you how it's done''.

Kill the mood? That’s a fantasy of mine haha.