Looks like he's cured....

You watched him do this, and yet you didn't break-up with him?

Now was he flirting or just being nice? Don't confuse the two. If it was at his house, he may have just been playing a good host. Being in his comfortable surroundings might have brought him out of his shell vs going somewhere else that could bring on the anxiety.

why do I get the feeling OP has a loose definition of 'flirting'?

You gave him the confidence to improve his game.

You have released his inner Ezio.

Speaking as a male diagnosed with social anxiety, it's a heck of a lot easier to hit on a girl that comes to your own house than it is to go somewhere else and flirt. The fact that she's all ready in your house for any reason at all is just a huge confidence boost. This is just an FYI, though. I'm not justifying his actions or whatever.

what a break through! be proud of his progression! hahah

You should leave him, I dated an asshole who was similar in the way that he refused to go out in public with me but had no problem hitting on other women. He's just going to end up breaking your heart, OP.

Looks like you been lied to