Most Helpful Girl
They probably are bragging because they want to make yiu jealous and they are immature. Sometimes they are still are mad at you. My ex bragged about him having a gf before me having a bf because he was immature. I told him i was taking a break from dating. Its just all so stupid. Plus all they want to see is if your gf is an upgrade of them. Or they want to show you he is an upgrade of you.
Most Helpful Guy
They're bragging because they're typically still mad at you, or they miss you.