Not sure if they're closer in other endings or plotlines, but in my first play through they had barely even seen each other. So in that version, I don't really see why they'd be together. I could see the possibility of them getting to know each other, but what about Luther? He survived in my playthrough. Seemed like a good match for Kara.
Ye tbh I don't really ship anyone with Connor, but I ship Luther and Kara, and Alice as their daughter- its adorable. Connor x Markus makes sense, because they have chemistry but Kara x Connor is a bit weird imo, but i like Markus x Connor & Luther x Kara