The couple elope since there's just no way the families will agree to the union, but return in a few days when they realize that the powerful dads are setting the whole state on fire as revenge against each other. Thereupon they successfully convince their parents for their marriage, but a small unfortunate incident results in everything going awry and in the kids' end.
That's the tale for you - the age-old stuff about kids being in love and their folks hating it. Brilliance would need to come in primarily in the depiction of the romance between the lead pair for the audience to be deeply attached to them (remember Segal's masterpiece?) and therefore still talk highly of the film despite it getting them low in the end, but the chemistry between Mahesh Babu and Aarti Agarwal positively sucks.
Part of this is because the tale concentrates more on comic fooling around between the two rather than on letting tenderness build in. The best love stories are all about the depiction of warm and tender relationships that get you completely involved with the characters. Think of Geetanjali, the last Telugu tragedy hit. The courtship in Bobby is too short and unconvincing - unrepentantly copying a Titanic
sequence - and the rest of the film suffers from poor conceptualization of romantic situations.