don't understand sushant's character

one minute he believes that vasu is bad and went to vikram. next min when vikram tells him its not true he starts crying.

i thot they had shown him to be of greater strength and character than that.

he didn't believe Vasu and vikram relatioship right away. He tried his best to find out the truth..he broke when he saw them together in hotel room, plus he bought what Vikram told him caz Sushant in his heart know Vasu very well..Vikram's story totally makes sense to him. He knows Vasu as a secrificing , mahaan woman..those acts which Vikram told him, all make sense..that's why he believed him. Plus he probably noticed that Vasu was never really happy with Vikram..she was only saying she wants to marry him!