That is very disappointing to hear. I feel that in a healthy relationship if one partner is uncomfortable with the fantasies and desires of the other that no one would be forced to do something they aren't ready for. I think that both my wife and I would be happy to keep something a fantasy if either one of us were uncomfortable.
The concept that someone can't control their sexual urges is bullshit. That is just a way to paint yourself as a victim and remove blame.
"I couldn't help it, my desire was too strong"
"If you were more supportive I wouldn't have had to cheat on you"
Pure crap.