Exactly. What stigma?
As a civil society, we should demand more accountability from our friends. Excepting extraordinary situations (which truly are rare), we should let people know there is a price to walking away from their marriage.
Friends should demand their wedding gifts back.
Friends should not simply continue social engagements as though nothing happened.
Of course it is better to do all of this while there still is a marriage, and let people know that you believe in the union. It matters. You don't just sign a paper and everyone else is supposed to forget.
Marriage is a public contract.
When people break it, we should let them know that it is a big deal.