I like it when love interests call my PC "My Lady" in historical fantasy settings... I don't see every LI doing it, but if it fits that certain chivalrous personality archetype, I think it's really cute. 
It really depends on his personality. For men like Fenris and Anders, it feels right that they'd call Hawke by name, they care very little for etiquette, or mantaining a dignified appearance. Zevran calling the Warden "amor" and "cara" in front of everyone all the time is also right for him, because he's so openly and shamelessly affectionate and just doesn't care. And then you have these more restrained men like Alistair, Sebastian and Cullen, and for those, calling the PC "My Lady" sounds appropriate and respectful, mantaining a proper distance while still being as affectionate as they can afford in public. And it makes it all the more special when they slip and call you "love" in public that one time, because they're so distressed/passionate/distracted/etc in that moment that keeping appearances is the last thing in their head.
Like, it'd be impossibly cute if Cullen called the PC by Inquisitor, My Lady, Trevelyan/Lavellan all the time, and then that one time when you come back to Skyhold with a sword impaled through your guts and bleeding all over the carpet, he freaks out and calls you "love" in front of everyone. I'd pretty much die.