Why are men like this?

My ex of 7 days just “accidentally” sent me a message that wasn’t meant for me were he was talking about some girl he had met who was ‘everything and was all about him’ which he then deleted 2.2s after sending. Like why do men do this? I’m not hurt in the slightest I just found it pathetic cause this is not the first time this has happened with an ex. Like who “accidentally” messages someone after 7 days. If he actually has moved on that’s great. I’m happy for him but like grow up, you’re nearly 40.