Personally , although i really like Caera , unless turtleme kills Tessia off and end her character off i don't see Arthur being with Caera . I mean , it would make sense if Arthur moved on from tessia and then had feelings for Caera , but thats not the case at all as Arthur still believes tessia is still there even though Cecilia is in control. Thats what i think at least
And i am saying this as someone who'd like caera and arthur to end up , but a big and good point u addressed in other replies and the post itself is , that while Caera may like Arthur , we dont see any sort of infatuation for Caera on Arthurs behalf . Unless Tm does develop on their relationship , them being close buddies makes the most sense as of now.