A woman on vacation has a fantasy built up in her mind, which includes new places, food, and phucking.
If she's with her bf and he doesn't step up to the plate and give her a good constant railing while on vacation, odds are she'll be looking to upgrade soon once she's back to daily reality.
So if you fail to get your stiffy on command, go down on her, lick her all over, take a shower together, play with her nipples as she uses one of her toys...whatever you got to do.
It would be different if these were her demands everyday after your 9-5 job and you were just tired sometimes and need her to understand your need to wind down.
But on vacation, a girl has this whole mental image about how it's supposed to go down and if you want to maintain her view of you as a high value you are going to have to show her a good time.