No, I don't believe that. I think it isn't necesary that everything must bad ending.
such as Pla Boo Tong literature of Thailand; the heroine name’s Uyai. She was a normal girl and her life was started with bad beginning. She was usually punished by her step - mother and sister when her parents weren't at home. A character of Uyai like Cinderella, she’s a good girl obedient, grateful, kindliness, friendly, patient and etc. The end of Pla Boo Tong, Uyai became a princess, because her goodness makes she got married with King Phommathat.
The story want to show that person who believe and do in good things, the result of a good activity will make their life success and happy. It means bad begining hasn't bad ending forever.