If i will saw my Girlfriend with other guy i really jealous,even i know he was just talking to her but i feel jealous.I really like her.Oh god,i will never forget her.
I don't think that I would feel bad if I were you. Life is too short for you to feel sad about a girlfriend. Afterall, she's not yours since you guys are not married.
You're being too paranoid about it, though my answer would also be "yes, I would be angry about it" but it depends on the situation and if they're doing unwanted things. At random moments, you see your girl with someone just talking on a coffee shop, would you be instantly be angry to her?. I have full trust to my girl and it means that if ever I saw her with someone, I'll just ask who is he... ... ...The worst part is your given example... I hate it when she goes somewhere and have fun with someone without even me knowing. ITS WAR if that happens! , but knowing myself, I would just let it be and break up with her, simple as that ... She have done something wrong and she must learn from it through the hard way... (I'm not saying this pertaining only to girls but also to us guys if we're caught cheating)