Lonely friend of mine

A guy we know was widowed at 47 , his wife died from cancer.
For a few years he refused any offers from friends to start dating. Then he changed his mind.
He went out in a few dates. Some weren't worth a second date. Some ended up in bed , some lasted a few dates but on the whole he just can't find any regular friend.
I invite him around every now and then for dinner and some drinks. He's a nice guy but seems stuck in his memories and too busy keeping his life on tracks.