After what happened with Pike, Bellamy was devastated. Octavia hated him, his worst nightmare was his sister hating him and he mad eit true by choosing the wrong side thinking it was the right now. You were his best friend since in the Ark and you were always there for him, actually you and Octavia were also best friends and she always shipped you with him according to how close you and Bellamy were. You never expecting their relationship to end up like this. First you talked to Octavia and then you went to Bellamy. He felt guilty, he knew it was his fault that Lincoln is dead and he knew Octavia isn't going to forgive him at least anytime soon