It’s just boring, and defeats the purpose of good story telling IMO. It’s either uninteresting showing very little, or it’s like porn, and when I watch a movie, I’m generally not in the mood for porn.
If they had great sex, it may not mean the same to everybody. But if you show them at a later point, like breakfast or something, and they are glowing and smiling bigly to each other, we all know what happened, and how it went.