I've been asked this question quite a bit and I thought I'd answer it as best I can. because I guess it confuses me too, why do writers as a group chose the genres they choose? and why do I feel compelled to write romance instead of let's say fantasy?
I guess for me it's what I've always thought of, most of the books on my book shelf are romance and all I got read when I was little were fairy-tales, and all the films I watched had some love in them ( I was obsessed with the little mermaid!). I guess I write romance because that's what I love. and it's weird because I've only ever really had one boyfriend (Whom I love) but he's not big on romance himself. At least not in the way most of my characters are with each other.
I love the feeling when you get butterflies before a kiss, or someone compliments you and you can just feel your cheeks go bright pink. And in my books I love exploring how different couples are in love. For example:
Annie and Carter hide their love from each other in friendship then when it eventually comes out they find themselves having to fall in love all over again after Carter's absence as Annie doesn't feel completely trusting over him anymore.
Jason loves Sabrina like she's a goddess. She's the only girl who ever made him happy and who he wanted to be a better man for, and when she leaves him he still wouldn't let anyone say a bad word about her. When he figured out what Dexter was doing to her, he felt protective over her and confused why anyone wouldn't love her the way he does. His love lasts over years of being apart and he doesn't think it'll ever fade.
because there's no limit to how much you can love someone, and there's no rule on who you can and can't love. Sometimes it's uncontrollable and just happens ever if you don't want it to. Even if it's wrong and will never work out. and maybe I'm just a hopeless romantic but I think it's the greatest thing in the world, and I guess I like seeing other people (Characters) feel it too, and get to participate in their love affairs too.
Sorry if this was all soppy optimistic ramble, feel free to share why you write your genre in the comment!