He's a boy and doesn't know how to act.
He's full of it
If it was me it would be because I want affairs like that kept privet between me and the lady. I wouldn't ignore her exactly but I wouldn't act interested romantically in her around people I didn't trust with my personal buisiness. It's just common sense to be discreet, people can use things like that against you and him as well.
Too bad we only have YOUR word on this