Did they really fight??

maybe the leads fight for real while filming the last few ep? like how can they lose all the chemistry between them in one go, the drama from the start wasn't the best but they are cute together and acting it well but then suddenly they lose it , it's like they don't even want to touch each other so write edit it. because no way they have all the fun before dating but not looking like couple after that. i just want to find why they lose that spark between them.

that could be a reason too they look so out off it in the last few episodes