Romance is not just a genre of fiction and movies.
One of the key ingredients to a dramatic story is romance. Even light fare -- action movies or comedies for example -- almost always have some romantic element to them. It may not be developed greatly, but it's there, adding depth and drama to the overall story.
I don't write romance stories, but I do include elements of romance in my works.
Usually, I have two characters both acting as protagonist. Often they can only be successful working together. Always -- I can generalize, since it's my writing I'm talking about -- one of them is male, the other female.
And just as I said "always" above, I'll say it again ... they always end up in a romantic relationship. Stress, fatigue, and striving for a common goal has a way of doing that to people. I don't play up the romance too much; it's much more of a physical, "chemistry" based relationship that forms because of the constant close quarters the two characters are placed into.
As I don't write erotica, I don't go into much detail on any sex that they may have. I will mention if they kiss, hug, or otherwise have some (non-sexual) physical contact. They fact that they have sex will be brought up as well, but the scene always "fades to black" once the sheets are pulled back.
What about you? Do you like to write (or read) romance in books? Do you want the steamy details or is the "fade to black" approach good for you?