It depends on the specific plot and character dynamics of the manhwa. Sometimes such a scene might occur if it fits the story and the relationship between the characters.
The 'Valentine Kiss' manhwa is about a pair who encounter various situations leading up to a passionate kiss on Valentine's. It might include their past, present, and hopes for the future, all woven around this central event of the kiss.
It's a romantic tale about a girl who unexpectedly finds love with a prince. There are lots of sweet and challenging moments as their relationship develops.
It really depends on the context and the relationship between the characters. Sometimes it's a sweet and romantic gesture, but it could also be inappropriate depending on the situation.