As much as they both look great together and all but I have always felt karan is utilizing this whole angle. If you are not fighting a lot in bigg boss you have to do something to fill up that void of screenspace. He likes Teja and utilizing that by romance track. Making himself a package with - playing games, making plans with umar and others, making bonds , at the same time romancing. So all of it makes a lot of content from Kundra's side for bigg boss. Also more content = more screentime = winning possibility - i feel this is what kundra thinks.
Now to spice things up he will distance himself with Teja. Cause always lovey dovey cuddly things can't happen. So will show some distance to keep things interesting for tejran shippers when they will sort things up and come together. Just like how it happens in daily soaps. Also he will want to prove that he can go against Teja if needed, thus not a kath putli or dominated by her! This whole coming together, being lovey dovey, then fighting, distance, again sort out things and coming together whole track may happen in a loop.
This is why Teja should just play individually now. She alone is pretty strong.