It's just hard to look at this revenge as a success. I mean, he and his roommate laughed at her for wasting ONE WHOLE HOUR of her life to drive over there for Valentine's Day, when he obviously spent more than that collecting and organizing the images, going to a printing shop to place the order for a bound copy of them, waiting a few days for the order to be processed and sent out for binding unless he paid extra for a rush job, then wasted his own hour that she also wasted driving there (sitting and waiting for her, plus wasted his roommate's hour as well, so they collectively wasted twice as much time as her just during that drive)...
The time these two guys invested is many multiples of the hour of driving they laughed at her for wasting, and they didn't even get the slightest rise out of her. And the guy probably has handcuffed himself permanently with future dating, and somehow managed to make an almost sympathetic figure out of the cheating woman he meant to humiliate.
It was just mediocre execution of a very questionable idea in the first place. And it even cost him money.