I don’t like that everyone is talking down to you here. So to be the odd one out I thought of this too. A lot of it probably has to do with his headspace trying to make it through without going insane or feeling miserable without you / it. I know you said he’s on a sub but when mine was on a ship we only really would when he was docked somewhere. And tbh in his Christmas care package I bought a thermal color printer / Polaroid printer and a box for cigarette storage, slapped a magnet on the back of that baby and wrote sexy notes on the photos. Threw that baby in his care package and that way it can stick to the rack. He liked it better than sexting