How do you know she is dating someone else will vary depending on how you guys live your lives, though if you do find out, best thing to do is help her find the other guy or you'll be stuck with her.
Why do you think so many Thai guys are able to have more than one girlfriend at a time and it seems the girls turn a blind eye to it?
Most men cheat for physical reasons and when for emotional ones, though why is it exactly that makes Thai girls cheat on their boyfriends and husbands.
For Thai girls it's not your normal reasons for the most part but some are, Thai girls are not only jealous but it's also more likely that your Thai girlfriend is cheating on you than a western woman would, the reasons why Thai girls cheat might even surprise you.
His 21 year old girlfriend doesn't go to college doesn't work and basically sits at home all day watching TV soaps, she has no interest nor motivation to go to the gym, go back to school,or join any sort of club.
So basically she has so much time on her hands that she's just bored, last year i saw her one day at a coffee shop in town.