He also talks about us getting back together in a few years when we've had time apart
Oh dear.
What he's asking you for is permission to shag around as he pleases, plus go travelling for weeks on end (will he look after the kids and do the same for you I wonder, if you also want to travel)?? And then, after all that, he wants to reserve you for himself when he's bored of shagging around....until he sees someone who takes his fancy.
There is definitely noone else involved but he has struck up a friendship with some people in their 20s who are in his gym and I am convinced this is playing a part
Maybe he's not actively doing anything with another woman, but it would surprise me if no young woman has inspired him.
He spends a lot of time texting one of the 24yr old girls
As I suspected then. Why the fuck is he texting another woman a lot, who happens to be much younger than him as well eh??? What kind of pushback have you given him over that? Doesn't sound like you have much, but you should. It's a bit too late now though. He's shown himself for who he really is.
You deserve more stability and love than this.
So I was just passing the hall window. He thought we were away but we'd come home and he didn't realise. Hes sitting in his car messaging someone on Snapchat. Didn't realise people in their 40s still use Snapchat. Wonder who hes messaging
They don't really. Snapchat is mainly for late teens / early 20s, and for people who want to cheat.
He's already on his way to becoming a prize idiot. In the end OP, I think you will move on from him and feel the benefits of it, once you've passed your kids being in their mid teens especially.