While I do love a lot of work that has them, I commonly dread romantic subplots because they are usually written without double checking how it fits with the rest of the story- let alone the pairing the creator had decided upon. Unless it's a creator I trust, I 100% expect a romantic subplot that gets tied up at the end to have failed.
Because how often do pairings like that get to stay together? When that surprise sequel comes out suddenly that pairing falls apart. They'll get into a fight that is out of character for both or one of them, or one dies, or only one of them exists to be the main character, or mentor/guide the main character. We never get to see the pairing work properly as a unit together.
Yes, in real life break ups happen all the time. But please consider the meta-context, because we don't see best friends breaking up all the time in fiction-land.
To me, if the couple only gets together near the end of the work that tells me the creator has no idea how to actually write a couple together. (Not to say this as a fact, just my cynical opinion as I watch so many good ideas die because too many writers only know how to write about conflict and nothing else.)