Its either:
1. Rin dosent accept the invitation and goes back with Senpai, and said senpai is gonna go like ''Oh no~~ why didnt you accept the contract'' blah blah blah, and Rin is gonna say something along the lines of ''Bcuz i wanted to be with you, is that so wrong'' and an arguement between the two ensues, and Rin looses her chance to become a star and senpai. Maybe even get another love interest or something.
Or
2. Rin accepts the invitation from the acting agency (dunno what its called), Senpai suggest they breakup cuz he's just in the way of her dreams, then a fucking timeskip appears where they meet as professionals, maybe Eiji is a producer now but that probably wont happen, and Rin greets Senpai with the Psuedo harem, AND WE'RE BACK TO SQUARE FUCKING ONE.
Honestly hope the ending dosent turn into a damn melodrama...