It's actually been years since I read this, but I was reminded of it today by one of Sean's status updates for Angelfall, the one where he laments that the MC and the angel are going to start romancing each other. I sympathized (though I haven't read Angelfall), and that got me wondering whether the romancing is inevitable or necessary to make a good book. 
 Skip ahead to the answer: it's not. Here's proof. 
 (Bear in mind that the following is from memory, and forgive me if I get details wrong. I think I'm remembering correctly, however, based on the reviews I've looked at.)(Also: I suspect there are spoilers, even though most of the book is kind of a blur to me. The important stuff is not.) 
 Ethan is from Athos, a planet populated entirely by men, and he has never seen women before. He has a male partner, I recall, whom he loves, and there is some artificial mechanism for reproduction. The book also has a plot, which I don't remember at all except to say it was serviceable and it involves Ethan having to join forces with a beautiful woman. 
 One of the reasons I don't recall the plot is that I spent the entire book waiting for the other shoe to drop, as it were. Waiting for this woman to turn Ethan "straight", or at least tempt him to experiment with it, even if he rejects it later. He's only culturally gay, after all. Surely the possibility is there. 
 Doesn't happen. 
 And it feels... great. I can't even tell you. They get through all the adventures and misadventures (was there smuggling involved? Something like that?), and then Ethan goes home to his partner, and you just want to give a very loud HA! because it is so unexpected and so rare and Bujold has played your expectations like a violin. 
 This is why she is the (Mc)Master, friends, and don't you forget it. Do you like your SF with a healthy dollop of intellect and social commentary? Sure you do. This is the breakfast of champions. 
 So yeah, Sean, I'd also kind of like to see the angel NOT fall in love with someone, just once.