You might be out of luck, but it also depends on how flexible you're willing to be with them. Is there an earlier canon point where they weren't as obsessed with her? Is there a point in time you can take him from where his romantic interests aren't all about her? Are you willing to, if you bring him into a game, work around the fact that you may not get a canon love interest and therefore might have to deal with "YOU'RE SO OOC BECAUSE X LOVES Y AND OMG" from ignorant assholes who can't understand needing to bend icness to fit in to certain places if you happen to maybe play out him moving on or understanding that game =/= home and have him embrace that?
Like, it'd be great if you could get your canon ship mate, but games are one of the places that crosscanon pairings are usually ok. And if you play a char where it's obscure enough that the idea of you getting a castmate or your char's partner coming in is so low, I don't really think anyone could fault you for moving past that, particularly in a smut/shipping game. There's kind of a lot more leeway for things like that in smut games, but even then, you'll find some random person that'll have a bug up their butt if you don't play out x exactly as their canon portrays. I was brought up on WG not too long ago for not playing out my canon pairing in a smut game, even though both myself and the player of the love interest had no love for the ship and had agreed not to bother playing it. Outside parties are always going to be your weirdest judges, but, if you feel like having something like that pointed out is something you can deal with and not get upset by it, then by all means, app them in. The idea that someone's going to shit on you for shipping your character in a shipping game with their not partner when their partner's not in game is something I can totally understand, but I also don't think you should worry about it. Smut games are generally more tolerable, both in terms of shipping and orientation.
Re: Characters who are very strongly attached to their love interest at shipping/smut games
Like, it'd be great if you could get your canon ship mate, but games are one of the places that crosscanon pairings are usually ok. And if you play a char where it's obscure enough that the idea of you getting a castmate or your char's partner coming in is so low, I don't really think anyone could fault you for moving past that, particularly in a smut/shipping game. There's kind of a lot more leeway for things like that in smut games, but even then, you'll find some random person that'll have a bug up their butt if you don't play out x exactly as their canon portrays. I was brought up on WG not too long ago for not playing out my canon pairing in a smut game, even though both myself and the player of the love interest had no love for the ship and had agreed not to bother playing it. Outside parties are always going to be your weirdest judges, but, if you feel like having something like that pointed out is something you can deal with and not get upset by it, then by all means, app them in. The idea that someone's going to shit on you for shipping your character in a shipping game with their not partner when their partner's not in game is something I can totally understand, but I also don't think you should worry about it. Smut games are generally more tolerable, both in terms of shipping and orientation.