I’m suspicious of my boyfriend and his new colleague

My boyfriend got a new female colleague about a month ago. He mentioned that a new woman started working there, and he started talking about her a lot. Every time he mentioned work he would also mention her. They both work at the cashier so they work together a lot. I wasn’t really bothered by it then, just by the fact that he talked about her a lot more than his other colleagues. My boyfriend is facebook friends with many of his colleagues, and after a week or so he was friends with the new girl. Then they followed each other on instagram as well. They also exchanged numbers, which I understand because they work together. I thought it was weird that they became friends on different social media’s so quickly, but then I found out that he had deleted the texts between him and her. I uncovered his deleted texts with her and they weren’t flirty or anything, but he would text her on days when he wasn’t working just to talk to her. He would mention his family, his siblings, he would talk about the most random things just for the conversation to go on with her. He talked about the weather, his pets, etc. She would go a few hours before responding back to him, and he would answer the same minute she texted him back. He doesn’t even respond that quickly to me. He was texting in a way that I haven’t seen him do with any of his colleagues. He doesn’t randomly text his coworkers on his days off like he did with her, he doesn’t tell them about his days or his family. It’s weird that he lets her in on him this way. Another thing is that he mentions me to everyone, he even talked about me at his job interview, but nowhere in those texts were anything about me. The way he talked to her reminded me of how he was texting me when we first started talking. He would use an overload of emojis and write in his accent instead of proper english.

The thing is that she is an older woman, about 35-40, she also has a boyfriend. She’s blond and slim, which is his type, she used to be a model for a clothing brand as well. But something about the way he talks to her and deleted their innocent texts, and how he always mentions her when talking about work makes me suspicious. I know that I should trust my boyfriend, and I do, but at the same time I know he has a history of cheating on his previous partners and texting/ flirting with other girls. I don’t know if their relationship is harmless and i’m just overreacting or if I should be worried.

I confronted him about it and he said that the texts between them weren’t flirty and that it wasn’t like that. He said that he deleted their texts because he thought that they were texting too much and that he knew that I would be mad about how much they were texting if I found out. The thing is that he was the one randomly texting her, and he knows that it was weird which is why he deleted the texts. He knows that I have a reason to be mad and not trust him. I don’t know what to think.