My partner acted so sus....

We were lounging in bed, doing our things that night and I borrowed his phone to take a picture since it had better quality. When I was browsing the gallery, I saw a screenshot of a different messenger account. My initial thought was that it was just from a gc of his friends but then it dawned on me that it wasn't downloaded, it was a screenshot from his phone. Based on the screenshot, here's the details

1. It was a dummy account.
   
2. There were two latest conversations with girls.

So, I opened his messenger and checked for another account but it wasn't there. Gave him the benefit of the doubt, and asked him about it. He took his phone and said he got bored and thought that he still had some dummy accounts that were still on Facebook. He said that he tried accessing the account and deleted it afterward.

But there were two latest conversations, right? I asked him what are those, and he said that he was just being funny and replied to conversations from 3 years ago and deleted his account after that. I wasn't convinced. So, I told him to let me see the screenshot one more time, but he refused. Repeatedly. Saying that if he lets me see the screenshot again, I might look for the names of those girls and chat with them. I assured him that I wouldn't but he still refused and kept on saying that it was nothing, that I shouldn't think whatever I was thinking - that he was cheating.

He said that he just opened the account, played a joke on conversations he left seen, deleted the messages, and deleted the account.

Then, I asked him to reactivate the account and let me see the messages there. So, he opened it in front of me and there are no messages there. No archive, no restricted or blocked accounts. He said he wasn't doing anything behind my back.

But I'm still skeptical since he refused to let see me the screenshot again. He deleted it from his phone, and even on the trash bin.. I kinda feel his saying the truth but I can't help but think so otherwise. It's just that I do not have any proofs at this point.