Not sure what you are asking for.
Not sure what you are asking for? A way to stop his romance - dead easy just don't agree with him on anything.
He isn't a vampire btw, he's a vampire spawn and very much a victim, a romance with him won't spoil your 'good' playthrough in any way, If anything you supporting him and helping him through his personal quest (you can look up the details of that elsewhere) can be very 'good' playthrough orientated.
If what you are asking for is to sleep with him before you find out he has unusual tastes in drinking habits I don't think that's possible as he needs to drink blood very early in the game and before he's been in the group more than a couple of sleeps, but let us know if you can, interesting
