What to do when someone likes another guy

Okey well i been going out with my gf for 2 years andbwe had our ups and downs. This week ahe told me she meet a new guy friend and i told her that if he liked her and she said yes.i told her its not okey when you text a guy that likes you she told me that she only wajts to be her friend i said okey. 3 says passed and she was being different and i asked her what was wrong sue said nothing and i asked her if she likes that new guy and she said no i told her not to like that from a 0 to 10 how much she gives him and she said 2 but that she loves me a lot and i trust her.she told me that that guy walks her to every class and that she likes it and that when shes with him she feel butterflies.she told me today she was mad at him because he flicked on her.she said that he told her to wait for him outside and she did.she likes him she told me.idont know what to do.what should i do