Honour killings usually refer to violence carried out by relatives in response to the victim’s actions (going against cultural norms).. Your definition isn’t correct..
There’s a very well-known case similar to the one you’ve mentioned here in the UK involving a model called Katie Piper.. and no, excuses weren’t made and the guy who attacked her (ex bf) was not labelled mentally ill.. Obviously that doesn’t involve honour but neither does the case you mentioned.. As has already been pointed out it’s about revenge..
The truth is that actual honour killings are linked to culture (not religion obviously) but not just desi culture.. Arabic, kurdish and other highly patriarchal cultures also have a problem with it.. Western societies do have plenty of problems but this isn’t one of them..
Btw you need to add the source for this article as well..