I like writing -and reading- romance as a sort of subplot, essential to certain characters, but not to the plot. And if a piece of media is aimed at a mature audience, both physically and mentally, romance doesn't have to be all about physical or 'romantic' interaction, but simply character interaction in general.
I like to write characters as themselves, making their way through the world in a way unique to that character only, and have the romance be almost unnoticeable, so much so that only the trained eye can sense the connection. When the romance is like this, it gives the reader a chance to expand upon individual characters and play a sort of game of spot the difference, and see the growth and change between relationships, whether platonic or romantic.
When I do make romance 'plot-essential' it is for the growth of characters and almost always involves some sort of loss, whether the life of one person in the relationship, or their loyalty. This amplifies the room for character growth a ton, since a major part of their lives was just ripped from them, and it forces them to come to terms with what they care about most, their personal life, or their mission.
I tend to dislike 'love at first sight/pining' a lot, but when it fits with the characters, I love it. Especially when unrequited. It shows a real difference in the two characters and forces the reader to keep reading painstakingly to see if the pining eventually pays off, or if something goes wrong (or both).
Usually, I also enjoy writing uneven relationships, where two characters seem to be in love, whether in a relationship or not, but they don't work for each other, whether because of their own internal issues, or the social climate/situation they are in that forces them apart. This allows the reader to see how the characters work together and also allows them to 'pick a side' if they want. I like it when readers have differing opinions, because debate is healthy.
And that's how I like writing romance!