When Sol got sick, Belén was blackmailed by Ramiro, in order to provide the little girl all the medical assistance she needed if Belén definitely left Martín's life, and so she did.
When Sol got sick, Belén was blackmailed by Ramiro. She became unable to adopt Sol, and in order to provide the girl all the medical assistance she needed, Belén should definitely leave Martín's life, and so she did.