Why Hide and then Run?

So I thought this movie was really good, one of the best from Indian cinema, but I have a few comments. If Ravi didn't want to go to jail because of his children, it's plausible that he disposed of the body, but why did he run from the police like a fugitive, making his crime much worse?? Also, Reena was being very stupid about the whole thing, one lie after another. She even had a fight and hit her boyfriend Raj, it's like she's going down the same path as Ravi did!!! Her behavior during the movie lead me to think that she cared more about Ravi than she did for Raj. She would do anything for Ravi in the movie, and completely disregarded Raj's warnings and advice.

I suppose that was the way the story had to play out for it to be such a thriller.

"I want ten chocolate chip cookies. Medium chips. None too close to the outside." -Howard Hughes