is it considered cheating or not
i recently saw a post on my fiance's fb account. his female coworker wrote "where you at" on his off day around 11 or 12 at night. i asked him who the girl was, and he said just a co-worker and they have a ongoing joke at work asking each other where they are at. i told him him it was flirting and i did not appreciate another woman asking where my fiance was on his off day late at night. he said it wasn't flirting.
but then i got curious and looked at his phone. they have been exchanging text messages for the last month. several of the text messages from her are about asking him when he gets off, they should do something after work, can he come in early to hang out with her, where he's hanging out at...and each time he responded with the times and what he was doing, yes they should hang out. definitely flirting. the last message was about him being out with a friend and she wanted to join, and he told her ok, then he wrote back to her and said change of plans.
i was out with my girlfriends the same night, and had texted him to meet me out, so im not sure if he changed his mind because i texted or he did not want to see her. also, the last text from him to her was asking her what shes doing, and she wrote back "im messed up right now and i dont want to say anything that will get me in trouble." and he wrote back "ok lol"
i know his work schedule and he has not been out late or not coming home, he's acting fine. we dont have any issues. everything is normal, so i dont belive they have hung out yet.
im really confused because is he just being nice, flirting or cheating? i'm not sure what to think at this point. im really hurt and confused by his behavior.