I never understood the concept of honor killings though.
If you feel that the girl/guy has tarnished your reputation, disown her/him and let them go their own way in their life. You have no bloody right to take their life just because they dont agree with your outdated concepts of honor/izzat.
And before someone jumps in - I'm not referring to this particular case bu also the honor killings in Punjab,Rajasthan, haryana and the UP.
Surprisingly I have not heard about this concept much in Bihar.
In UP I think its only the Western parts where there are cases of honour killing. In my opinion this is because of whatever happened in the past. All these areas faced the brunt of foreign invasion in the past, multiple times. This has made people of these regions over protective(ironic) and possessive about their women folks. It has sorta become part of their identity and culture.