Nooooo! I wan them all to be togetherNothing wrong with Lena being selfish and telling Holly not to sleep with random men because she wants to do it herself.
This also opens alternative scenario -- Ian breaking up with Lena during the beach house trip because of news of Lena cheating on him, and Lena and Holly then getting together as exclusive pair. Which is cute in its own way, given all the pining they've done for each other (but held back because of Ian) during the earlier part of the game.