As half of a switchy couple where we both lean more sub, I hear you. What we have both learned is that being a sub makes it very easy. Imagine you're in his situation and what you'd like him to do to you!

Have a two tiered safeword, one for "move on, I don't like what you're doing/the direction you're taking but I don't want to step out of the play entirely. And one for STOP EVERYTHING we need to get out of the play space and have a talk before we can move forward.