Every time I tell him I made plans with someone else at that crucial point where he confesses that he loves me he forcibly demands that I drop them and whoever else I was dating. He tries to take all of my magic, and one of the endings with him ends up with my magic brutally taken away because I broke my word when I said hi to him. A lot of other people have had their hearts broken by him, not just girls but even William! He's cruel, possesive, emotionally and physically manipulative, dangerous and he even tells the PC character outright that he's not a good guy. He writes you love letters where he tells you that he'll kill anyone who you don't like for Goddess' sake!
All of which makes me wonder, is pursuing him really romantic? He has all the signs of being an abusive boyfriend, and yet just because he's cute he's being forgiven for all his heinous crimes? If he was a normal guy girls would most likely still fall in love with him, but their relatives might call the police and have him arrested as well as writing up a restraining order against him for the girl's own good. (Of course usually this means that the whole family has to be uprooted and they have to change their name, their looks, their personality, their jobs and they can't let any of their loved ones know about it but sacrifices have to be made, especially for your children.)
Now whether or not the woman stays away from him is another story entirely...
And whether or not this all just adds to his charisma might be subjective as well. There are people out there who likes bad boys, I must grudgingly admit, but I for one hate that type of person. So do forgive me if I seem a little harsh here when I talk about him but I am very much biased when it comes to him.
Personally I think that while the game certainly makes all of this seem romantic, I would most definitely NOT want to have a boyfriend like him in RL. Actually, I don't think I'd even be able to become friends with him. I would most likely kick him where the sun don't shine and then tell him that he's worth less than dirt underneath my shoes. In fact, I'd be hard pressed to not kill the son of a shark.
Someone like him wouldn't be worth all the trouble you have to go through to be romantically involved with him. People who are morally questionable do not just change through the power of love, no matter how much Hollywood and bad romance novels might try to convince you. Someone like him will most likely get you killed.
I would rather be that spinster who lives with 30 cats than to have to deal with someone like him.
At least with cats I know what will set them off. With him if I so much as look at another person funny he'll most likely try to kill them and me.