Is texting other women inappropriately and flirting conversations considered cheating or wrong for a married man?

My husband and I have had a 2 yr disagreement on this topic and I would just like to find out what other people think. All of his friends with the exception of 3 childhood friends are women. He has always told me that they are all strictly friends nothing else but recently I found out he ended a friendship with one of the women because her inappropriate talk and their flirting had went to far. I asked him if he talks inappropriately and flirts with all of the women friends and he said yeah at some points in time he does. He sees no wrong in it, he says its just silly fun and he has no feelings for the women so what’s the problem. I think he is putting himself out there like he is a single man by carrying on all of these relationships to begin with and while he doesn’t have feelings and see it as nothing big maybe the women he is texting feel differently. All of the behavior also makes me feel inadequate because he feels a need to reach out to other women. So is this something married men just do and is normal or should I be concerned?