What would you do if you suspect your partner cheating but have no proof?

A couple months ago I saw some questionable texts on my partners phone. It was during his business trip, he met up a women that he met through a common friend and from what I know is that they had a dinner and he also offered to pick her up late at night after an event. He also called her a bunch of Ubers because she said her credit card has issues. I only saw parts of the conversation and confronted him. He told me it was simply for business purposes both the events and the dinner but the fact he didn’t tell me anything about it seems quite sketchy….he did promise he will tell me everything and about his whereabouts and he has been proven to be pretty trust worthy after that. I let it go during that time but for some reason my suspicions are creeping up lately thinking maybe I was too naive to have believed his explanation. I do know I still want to be with him at least for now since I don’t have any further evidence of cheating but I’m definitely struggling mentally about the incident. I’m also tempted to keep digging about it but not sure if even I go through his phone will I find anything at this point. Any advice?