For what it’s worth, I think their friendship worked because it was perfectly genuine, and because Jack was never plagued by any doubts about his own sexuality.
Most of the homophobes I’ve met are insecure – they carry on as if they have to prove something.
In fact, I was once told by a very highly regarded psychiatrist that the only people who worry about anyone else’s sexuality are people who aren’t confident of their own sexuality.
One of my dearest and oldest friends is a buddy I met at school nearly 60 years ago. He is 100% str8 – he’s always been one of my closest friends, ever since we first met – I’ve never been anything but homosexual and he has always been aware of it – and it’s never once been an issue between us.