Would you think this potential couple is a good idea?

The guy is a latino man who seems to have a dark side to him...hes quiet and has the "I will kill you" look on his face most of the time. And hes only 5'5

Shes 5'10 so I think they are odd and

she is also not really aware of his life style

I should have started with that...hes a violent man who has gotten into some street brawls and shes this tall blonde blue eyes naive girl. She can get him to laugh so I do think he actually cares about her. But I just think she just sees his smile and the way he treats her and thinks that is who he is

and I am not sure if I should inform her that hes not a good guy and nothing her father would want her messing with.