i think I'm being paranoid

Okay so basically me and this guy are idk like unofficial but we still act like a couple and so on. So basically we were having a normal conversation last night about PlayStation and he just sent me a dick pic like "boom you weren't expecting that" and obviously the conversation got fairly sexy. Anyway the same thing happened tonight, absolutely out of nowhere again but like I've stated over thinking and I'm like if he was just sat there gaming and I wasn't even showing him any pictures of me or talking about anything sexual then maybe he's talking to other girls in that way and they're making him hard? Like there must have been something that's made him go like that? Idk I over think too much and although it's not serious between us I don't want to be taken for a mug like I'm previous relationships 😕