Is it ok for a married man to develop new friendship with women where they are texting & long phone calls?

We have been married 12 yrs. He cheated 8 yrs ago and we had worked through it. We moved here 2 months ago. In our old town last yr we had an "issue" with a girl he started talking to. First without me knowing. I found out, he continued until she told me they were having an affair. Huge fight and he stopped talking to her. There were a couple other girls that he texted and then stopped when we moved. He continued to talk to one until I made enough of an issue about it and he stopped. Although she continues to text him. Now the issue is he is talking to someone local. I dont know who it is or what they are talking about. I do know that it is only when I am not around and they talked for well over an hour or several times throughout the day. I have told him I am not ok with him developing "friendships" with women, esp after what has happened in the past. He said it shouldnt matter who he talks to or what it is about because he is at work when he should be and home when he should be. I feel that because he hides this info from me then its not innocent. Whenever I try to talk about it we ended up fighting then nothing changes. Am I over reacting to him developing new friendships with women that he keeps hidden from me?