As far as romances go, I like to have enough options that I can find one that makes sense for my MC for a certain play through. I think the most important thing about romances is pacing and variety. I don’t want to feel limited- as in, there are only two options and one of them is such a jerk you can’t stand them- and I don’t want it to feel like “Hey, I really like you. Now let’s get married.” Lastly, I think LI’s should be an integral part of the plot even if your MC doesn’t romance them.
This pin describes this perfectly!
For length, I think you should make it as long as it needs to be to tell the story you want to. I don’t think a longer game is automatically a better game and you can pretty much always tell when a story has been stretched out just for word count… That being said, I think it’s a good idea to make a lot of side stories that subtly change the ending. A short game can have a lot of re-play ability if you have things like Easter-eggs and secret achievements- like a near-impossible romance with a late-game NPC- or maybe getting an unusual solution to a problem (singing your way out of a situation? Throwing a slushie to defeat a your arch-enemy?)