I would be surprised if I didn't think about it. In fact, I believe I did. Are you sure you can't get that scene at all while that is going on? I'm not going to dig through the code right now, but I seem to recall there being a way to gain that scene back after entering a relationship with Evelyn, though I may be mistaken.
In any case, that scene is indeed gone as long as you sleep in Evelyn's bed, and it wouldn't make sense to offer the ability to sleep in your own bed once you're in a relationship. Evelyn wouldn't understand.
That scene is always available in the gallery anyway, just like every other sex scene.