My sister's name is amber. firstly give him a chance to explain, but if it is obvious that he is messing around and stuff, don't get mixed up in it and just never talk to him again, leave him and forget him.

Amber, sounds like you would be a prime example of why I advocate girls keep their panties on until their wedding night. I am going to assume that you have slept with/had sex with this guy. He's just moving on to the next girl and might let you know when he finds her or he may just let you find out for yourself and really hurt you.

Us guys have been doing this sort of thing for centuries.