my husband and I have been together for 14 years and married 4.
Many years ago he was messaging a girl he used to work with, talking to her in secret calls and would delete messages off her and got caught walking hand in hand with her in a local park. We sorted it and moved on. Every couple of year this girl pops back into our lives by messages - don’t know who starts but it happens.
I don’t go through my husbands phone - I used to when I was concerned but haven’t done it for years now. We’re currently on holiday with family - about 20 of us and he had taken some photos of me him and our LB on his phone. I air dropped them to my photo - with his consent I always ask out of politeness more than anything and there she was on his most used contacts on Facebook messenger. She’s back. He said he has been talking about general things and messaging her while we are on holiday but deletes every messages after he send it or receives one so I don’t get upset. He’s reassured me that there’s nothing to it but why delete messages if it’s just friendly??? Is that strange to anyone else??