Apparently, the 24-year-old isn't willing to negotiate a contract renewal and wants to leave the club this June. His current contract runs until summer 2018 and Real Madrid will have to sell him, if they do not want to let him go for free.
However, the club's sporting directors haven't offered him voluntarily a new deal like in Modric's and Bale's cases, which made him change his mind and led to the decision to leave the club.
Furthermore he is struggling and doesn't get enough playing time which motivates him to look for more attention at another club.