Anedote time!
The closest I've come to an "uncomfortable situation", I was GMing a 2e Dark Sun game. Everyone had rolled up wild talents, and a woman player had... I don't have the book handy, it's an 'attraction' talent, and she used that thing unmercifully on male NPCs. They were parleying with elf raiders, and she used the ability on the raider chief. Up until then, I hadn't wanted to "go there", but the situation was pretty clear to my mind. She successully used the ability on the raider chief, and I role played him "Execute them all, but the woman. Have her taken to my tent!"
I'm not squeamish, but I run a PG-13 game, it was in a public place, and the player's husband was also at the table. So I had no plans to run a "rape scene". They wound up fighting the raiders anyway, so it was moot. But for a while there, I was staring down the barrel of resolving a rather ticklish situation.
So my "uncomfortable situation" was completely driven by the actions of the player in question, and from my read on the table, I felt pretty justified in how I ran the encounter.