Will Clarke and Bellamy become a couple in season 3?

No.

Since Lexa's in the finale, I doubt it, but I think they probably will get together in season 4.

No one knows. I'm pretty sure they'll become a couple in season 4, but as of season 3, there are not many chances, even though there is a hope for at least a kiss.

I really hope they do! They have so much moments where you see their eyes meet like two people in love.