Lust can be very deceiving. Ego can be very deceiving. Be careful that you are not being deceived.
There are two separate issues: whether you can just tell that someone is right for you, so soon. Cheating is the other issue.
Cheating is bad. For you and for her. Be a real man and don't do it.
Now if the person who just walked into your life and you felt they are "the one" (like a movie, so dramatic
) just remember, there will always be someone "righter," more beautiful, more attentive, more exciting, more sexy.....on and on, until the day you die. Do you want to be a slave to that kind of thinking?
Jennifer