Mischa felt his heart pounding when he heard her love confession. He could tell that she harbored feelings for him but it was different when he heard it with his own ears, that Vega loved him back.
He remembered feeling anxious for the whole year while waiting to see Vega again after her decision to forget about the past... as her way to forgive Ren.
Mischa was worried that Vega would fall in love with Ren when they finally met again. For him, it was like waiting for the extended death sentence. His death sentence.
If Vega really would return to Ren, and marry him for real.. then Mischa would not have a place with her family.
He had no one but them. After Lisa broke up with him and later died, Mischa had been so deeply connected with the Lindens. Not only because Elios Linden was his foster father, but because he had spent so much time with the family.