There might be some scientific basis for why romantic movies make for good dates. In one study, participants were asked to watch a romantic movie and a violent movie, and watching the romance stimulated the viewers' "implicit affiliation motives."
These motives are unconscious desire for close friendships. Plus, in men, watching the romance decreased their power motives, or their unconscious desire for dominance.
Changes in implicit affiliation and power motives are associated with changes in hormone levels. For example, the viewers who watched the romantic movie experienced a temporary increase in progesterone levels. But with the violent movie, things were more complicated.
In The Mood For Love
The reaction to the violent movie seemed to depend on the amount of testosterone the subjects, both men and women, had in their blood before watching the movie. Men who started out with high testosterone levels and power motives experienced the biggest increase in both.
In contrast, women with higher pre-movie testosterone levels and power motives experienced a drop in both, while women with lower testosterone levels became downright uncomfortable. While this might have to do with the minor role of female characters in the particular violent movie the researchers selected, this study still helps explain why certain people are drawn to certain types of movies.
So as far as the ideal date movie goes, until you check out your partner's video collection, it's probably safest just to go with a romance.