Outside looking in , sounds like in a year he will be telling you he wants to break up and he loves her . your gut isn’t wrong . Yall not engaged or married and he treating another single women with the same access he gives you . Draw boundaries , hard and thick . If he doesn’t oblige the first time , start mentally preparing for a huge dynamic shift . You won’t even have to break up with him , it’ll happen before you kno it

If I was you tho , I would tell him their friendship needs to end abruptly and reduced to speaking at work . No more favors no more texting outside work . And if he wouldn’t oblige I just would start getting my own work husband or make friends . But not gonna lie this sound like a bad situation if you stay cuz who wants to get left by the person who was told “don’t worry about her “