Most Helpful Guy
He is your ex, so why bother about this? does it affect you or are you just asking this out if curiosity?
I mean there is a chance that he likes her or finds her attractive, possible.
Most Helpful Girl
That is a little creepy and weird. Is this girl someone he is seeing or talking to? He might like her or if he knows you notice him changing it and stuff he may do it to try and make you jealous.