Tech Question for iphones PLEASE HELP?

I know my relationship is messed up obviously this shouldn’t be an issue but I need answers.

My husband looked at my phones text usage time and it is 2 hours longer than his. I don’t text with anyone but him and occasionally my family. He uses his text for work quite often.

He was really concerned that I was texting someone and deleting the messages and that is why mine had so much more usage than his (so f***** dumb).

Does anyone know what would cause this to happen? I often leave my text screen open after sending a message and I noticed he always closes his immediately.

How does apple track text usage time?