He ignores an ex Ffriend in front of me, why?

[AQuestionOrTwo]

This happened a long time ago.. but Im still curious to find out what U guys think:

My boyfriend and I, together for a few years at the time, are sitting on the terrace of a neighborhood restaurant one morning, a girl passes by and says hello to him and he ignores her. I ask him who she is? He replies ''she's crazy''.

Some time later, I see that he had wished a girl happy birthday on social media a while back. I ask him who she is, he finally tells me she's an ex ''intimate friend''.. the same girl who had said hello to him at the restaurant a while back. I ask him why he ignored her in front of me, he replies that he didn't want anything to do with her, yet he had wished her a happy birthday a few weeks or month before the restaurant situation. Why did he ignore her in front of me? What is the REAL reason? thanks!

[RavVid]

Well I would take intimate friend to mean they were fucking at some point. Probably he sees her as trouble wrt you and doesn't want that.