Oh god this happened with friends of ours. I introduced a colleague of DH to a friend of mine. Their jobs had some overlap so they'd met but didn't know each other.
I thought they'd be a good match and we're exceptionally sociable so arranged for a few events they'd both be at.
They went on a few dates and he was horrendous. Far too much far too soon completely putting my friend right off.
Bloody DH failed to mention when said friend had a drink he got overly emotional/clingy/needy.
He was turning up at her house and leaving presents. Sending drunk messages (after she politely told him that they should just be friends) how much he liked her etc The messages then started coming to me about how much he admired DH & I and hoped we'd all do something again soon. We had him round, on his own, and he got so drunk and emotional he ended up lying on the sitting room floor weeping and cuddling the dog.
He's a grown man in an extremely responsible position/job with two teenage DC ffs 
We've now had to cut all contact with him, thankfully a transfer at work means DH sees less of him as does my friend. We think he's just lonely bless him but regardless of how we try to help we get it wrong 
Walk away OP, in fact if your instincts scream it, run away....