I'm not too up to date on every piece of story, but the basic gist is that on the relationship chart seen in-game, the doctor, Kal'tsit and Amiya are linked together. Kal'tsit's attitude towards the doctor is also very passive aggressive and snippy, which could be interpreted as ex tensions. Might be other 'evidence' too.
Is it just me, or does fanart of Catra with her new hairstyle look way more cuter than before?
Oh and adult Catra is just about to enter MILF territory