I know a man through a sport we both do. Both middle aged and single.
I don't know him well but we mix a lot in the same circles.
He always seems pleased to see me and makes a point of chatting at events.
He contacted me to ask how I was when he heard I was ill
He sometimes messages random comments about sports teams we're both interested in.
However he's never "bitten" when I've put myself out there. Admittedly I've never been completely back and white about it, but:
After one event we'd both been at, everyone else was going off to do family things and I suggested a beer. No he's got work to do that afternoon.
I saw him this morning, chatted for quite a long time and we were both undecided about an event tomorrow. I've decided to go and offered him a lift (car sharing is common for these events). He's decided not to go, he's going to train on his own so he can do some work after.
I know he has taken on an extra project in addition to his day job because he's told me about it in quite a bit of detail.