Baed on your past experiences with gf/bf what are the chances she's seeing this guy/likes him based on what i just told you?
Most Helpful Girl
Are you in an actual relationship or just went on one date? Because if it was one date then it's possible she didn't have as much interest in you and found another guy she likes more.
Most Helpful Guy
If you aren't in a relationship with this person, she is probably just dating around and is attracted to this person more. In which case it isn't cheating.
On the other hand, if you are in a relationship with her, then you should be on the lookout, because she is searching for someone new.