Girlfriend unfaithful?

Okay so on numerous occasions I have seen my girlfriends texts to guys when the guys are saying oo we should cuddle and you can't resist kissing me now she never says anything back like "yes! But shell wink and say you had your chance" but continue to be playful texting, she also has friends that she met on the internet and only one in real life and she is constantly talking to them and sometimes wanting to meet up and she will never come clean to me about it and tells me that rthey are just friends but there are times I've seen her say (while we were together) how she wished they woulda kissed when the had the chance and where things could have gone, and that ten months previous to this she compketely professed her love for these internet guys but totally denies to me that it was anything like that, but I have read things that she has written that completely suggest other things. More recently I found her "having dreams about some guy at work that she thinks is hot no ual but still. And texting guys from her work and when she talks and texts them she constantly tells them she's bored or not doing anything when she is with me, we live together and do a lot together but in her texts it honestly seems like she's single there are no hints saying oh just watching a movie with my boyfriend, its i"I always watch movies alone". Should I be concerned