This is just a lovely portrait. Who knows what it means? We are not ourselves, how can we know what the parties think?

Maybe the girl just thought this avatar was cute and liked it, so she changed it, that's all.

If you want to know what it means, you can ask your girl directly.

Ask the girl directly in a relaxed tone: how do you remember to change your avatar, but it's cute.

I mean, it's not good to be concerned about each other after breaking up. Maybe girls change their heads just to get your attention.