My books have that exact same tendency! Then there are the books where I deliberately incorporate romance because I think I need it, and then realize I don't. Like the Last Wizard. I created a female character and she still drives me nuts because she doesn't help the story. 
I think a lot of stories end up as romances simply because there's a great deal of romance in the real world. And it's an awesome way to cause character conflict. As a girl I think I also have a desire to balance the scales of male and female MCs. Books with only male characters can drive me nuts... although I have another reason for that too which is totally irrelevant and unrelated.  
 
 Prince of Yen is a fairy tale, and a romance. 
Legend of Darmoor is mostly romance. 
Trice is about the two MCs, who do marry, so it's also a romance. 
The Last Wizard is not. 

Lightning Ranger involves romance, but it's not a main theme of the book. (Not sure what the main part of the book is, actually.) Part one is a romance, part two is not, and who knows what part three is going to be. 

Heroes of Ynoureth actually has two romances. Dudley and Sianna are the main ones, but also Lida and Rusha. And Daybreak and Tarique, but I don't remember what I did with them. Daybreak was mad and Tarique was suicidal so they'd make an interesting pair... unless it was Tarique and Lida. I can't remember now. It's amazing I can even remember these guys names at all. (There are seven MCs.) Daybreak's fiancée was murdered by her father before the book starts so I don't think I gave her someone else...
Anyway. 
The Third Earth... well... it was supposed to have a romance. But David was a lot older than Suzanne, and I was a little worried about that. It was such an unusual situation I thought perhaps I was being overly ambitious... Suzanne's really remarkable though. So I might keep it that way. I just don't want to sound too much like Elsie Dinsmore. 

City of Lies doesn't really have anything you could call romance. It's generally assumed that Illia falls in love with Ia'tahz, but I never give any indication of whether or not he returned the feelings and then I kill her anyway. 

The Gatekeeper's Secret has romance too! *stares at statistics* I suppose one could say I have romance in most of my books. 

 Maybe I should do something about that... although I really didn't like Celeste. She's kind of the setup for the sequel though. I either need to completely change her character or find some other way of... messing up the ending. 
All right, enough rambling on my books. 
