My bf does regularly inquire if I enjoy our escapades and it never turns me off. Communication is very important for a satisfying sex life.
Personally, my body reacts differently with each session. Sometimes mild, sometimes with more vitality. It's not always the same and the only way to measure is with communication and honesty. My bf uses the approach that I can be open with him without judgement, there are times I know it ain't going to happen for me and I tell him I'm enjoying and that's all it takes. It's not an indication to him that something is wrong and he doesn't take it personally.
So, I wouldn't get hung up on it. Talk about it. It is the most intimate act on it's own communication shouldn't even be an issue.
goodluck
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