Let's rephrase your last comment more accurately

IN MY EXPERIENCE sex always feels good, doesn't matter if it's love or not

The most obvious counter example is rape - where the victim has no control. In that scenario sex won't feel good.

So what went wrong? Lots of possibilities: loads of guilt, your partner was especially skilled at what he was doing, you were worried about being found at it...

But the real question is what lesson you're taking away from this experience. And that you need to answer yourself rather than have me speculate.