My idea is, that, in effect, a lesser version of the valentines thing could be year round. It would be an optional antag, and have 2 ways of triggering.
1: a very rare roundstart thing that applies what normally happens during valentines
2: a more common, roundstart or midround thing, that applies to a few people at most.
I think this would be a good idea due to the fact people seem to act nicer during valentines, and are forced to keep other people alive, leading to a general more fun experience. If this were to be implemented, however, i would expect that some kind of message warning against doing ERP if you want to be able to be this valentine thing would be necessary.