Dating

Found oit my fiance exchanges plenty of memes with his attractive coworker. Should I be concerned?

My fiance (28m) has an attractive female coworker (22) who he has been friends with before he and I (28f) started dating. He's been her designated driver, she is open to him about her dating life, he likes her selfies on instagram, he always asks of her weekend plans, and she calls him often to ask for favors. When my fiance gets home from work he doesn't call or text as much as he used to. I asked him recently how his female coworker is doing and how her relationship with her on and off boyfriend is. He said they are not doing good. A while back she mentioned how she sent him a meme on instagram. She has been the type to text him about work or about dating issues while he and I are together. I asked him recently if they share memes with each other. He said yes, on instagram. I asked if I could see them. He was hesitant at first. When I finally saw, I found that they exchange tons of memes evertday. Sometimes more than he sends me. My fiance doesn't share memes with me everyday. He and his coworker see each other 5 days a week while I only see him 2 days a week. I expressed to him that I felt uncomfortable about it but I am still bothered by it. He said that he would stop and probably tell her that they should not share memes anymore. He has not yet told her. After work he has been going online frequently and not texting me back. I feel insecure that he likes this girl. When she is beside us, my fiance does not show PDA. He has not updated me on whether they stopped sending each other memes. Is my fiance crossing the line with sending her memes?
Found oit my fiance exchanges plenty of memes with his attractive coworker. Should I be concerned?
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