Should i go ahead & ask him out....?

ok. so theres this guy. and i am really falling for him...but he has a girlfrand. he hasnt told me he dosent know her, but he told me e dosent know much about her. & honestly, i think he may like me....not sure...hes kinda a player...but he is the type to dump his gf for someone else....should i just go ahead and ask him out? or let him ask me out?