LOL if we go by the "if I was treated in this manner" argument then umm no normal girl would fall for RK to begin with...the man did a 4 phere shaadi with Madhu and Madhu took that as a license to fall in love with him, PRAY for him, give him her own blood...if anything is preposterous, it is THAT to begin with...a man who only gave her humiliation non-stop and treated her like dirt, that is the man she chose to be so sympathetic to...so she shouldn't have fallen for him to begin with.
So since Madhu already did that, why is it so unbelievable that Rishbala still work as a pair? Cuz the fact of the matter is, they are a twisted, angsty love story...RK is a very very twisted soul who loves Madhu in his own twisted way...the "unwed" drama and all thereafter has just added a darker tone to his obsession with her...this was never a roses and violins story...so those who were expecting that are maybe not able to appreciate this anymore...and Madhu is a strangely kindered spirit who GETS him...that is why they are bound together...new characters come and go but this strange dark bond b/w them draws them to each other regardless.
They hate and love each other with equal all consuming intensity...and that is why they are endgame.