Yuvi does a Prison Break because everyone tells him his case is hopeless, and he simply cannot live in a place with no washbasin and no hand sanitizer, not to mention a filthy cell where rats roam even in the daytime.
We've seen the police station, it's not that secure a fortress. Yuvi has been left sitting on that bench, sees a rat and takes off. He runs out of range of the chasing guards (our Yuvi's used to running, and policemen are old and fat and out of breathe in no time) . Obviously Yuvi phones Su, who packs a bag, grabs whatever cash is around, and picks up her Scooty and Yuvraj, in that order, and for once doesn't give bhashan about doing the right thing and surrendering, because dadi has filed a case against HER for stealing her money.
So our lovebirds are finally out of BH, alone, and in hiding. Kya kya nahi ho sakta.
Eventually, of course Radhe's truth comes out, Yuvi gets a slap on the wrist for escaping custody, and by the time they return home, Yuvi has his arm around Su and dadi looks aghast as he nuzzles Su's neck in front of her. Yeah, now try getting her arrested, BQ.