I have never had issues with him about other old female friends he hangs out with every couple of weeks as those are old friends.
Based on this info:
Q: Would it be OK for you if you were in the same situation?
No I personally wouldn’t be too happy. Often you instincts are right when it comes to this kind of thing. It’s fine for guys or girls to have friends of the oppersite sex, as long as it stays that way. Sometimes there are signs that need to be paid attention to.
It sounds like something been going on for a while wether it’s good friends it sounds like it’s turning into something more or has done already.
She left the company, and they still see each other? She’s going round his house for dinner, so they are alone together? I think I’d be more annoyed that he ignored that fact you told him you were not comfortable. Have you spoken since?
I could understand a work group thing, that’s socialising and getting to know people. but one to one alone? Nah. He could be pushing your buttons to see how you react. Maybe he’s insecure. I know this all to well, my ex did this too, when he went to uni, which is one of the reasons why he’s an ex!
But dinner alone together makes it sound like a date night.
It very easy for him to say things like, ‘we’re just friends’ and ‘you should trust me’. For you, its not exactly reassurancing.
He shouldn’t be making you feel uncomfortable or worry. He actually making out he’s seeing someone else closer to his home. Whether he is or whether somethings actually going on, it’s a sh*tty thing to do.