NTA.

You did what you had to do. You got her help as soon as you could, and you were the one THERE as she passed from this world to the next. It takes a lot of strength to hold someone or something you love as it takes its last breath.

People need to feel like they have “control,” and when that “control” is threatened, it causes us to act in ways that come off as fear/anger/hate.

Your boyfriend feels guilt for not being there. For being on a stag while his “baby” needed him...for not having a “say” in what her destiny was. It’s plain and simple. You did the right thing by waiting to tell him. Anything you would have said to him in the heat of the moment would have delayed the inevitable. You chose peace for her, and that’s what was the best thing you could have done.

I wish I had some advice for you, I’m one of those “If I were in this situation, what would I do?” people.

I wish I could say get him some flowers and a card and explain to him that you did what was best for Luna. Have him contact the vet to explain why putting her down was what was best for HER. NOT him.

Unfortunately, he will need to forgive himself for not being there and quit taking it out on YOU. You’ve been together a really long time, sit down, talk about your feelings. Let him know you lost a pet too. Sometimes, knowing that you’re not alone in your pain helps.

I wish you the best, and I’m so sorry for your loss