My ex wants to talk to my BEST FRIEND about something?

So me and him were engaged had a miscarriage broke up and been emotionally tied ever since... I'm moving to another country this week and my best friend sent me a message asking if they can talk next week? He asked if he can see me before I leave and we meet up tomorrow, I have no idea what to talk about, but why would he talk to my best friend AFTER I leave?