My Girlfriend's Insensitive Comment About My Late Husband's Possessions

It sound like you're both grieving but in opposite ways she's externalizing while you are internalizing. I seriously recommend finding grief counselors for both you and her.

We all grieve in different ways. My gut tells me it was grieving. I know things will work out m.

It's good that she apologized, but something I think is forgotten is how it affects you in that moment. Setting boundaries and talking through things calmly and rationally can help, but I think getting her a therapist and maybe even seeing a couples counselor would do some good. Another thing to remind her of is that you have time to accumulate your own things as a couple, and spending time together doing things you guys love is a good way of bridging this gap she might be feeling. You have to remind her that her outbursts don't just effect her but also you, and sometimes just saying sorry isn't enough and that's okay. It's not your job to fix her or be her therapist. There should be just as much giving as receiving on both ends, sure you can talk to her about expressing her feeling when she feels them rather than letting them build up into an outburst, but it's not your job as their significant other to fix them. You can lead a horse to water but you can't make them drink kind of thing. They need to take the first step to understanding their grief and the best way to do that is through therapy or counseling. You should have to be their punching bag that will always forgive them because you're a person too, and them acting the way they did not only effected then but you too. It's okay to forgive them once, but if it happens repeatedly with the same outcome, even after talking to them, forginess is not something they've earned. You forgive someone trusting they won't do it again. (I'm sorry if this is long, tl;dr talk to them about going to therapy if they already are consider couples counseling. Just because they apologized doesn't mean you have to forgive them, especially for how they made you feel in this situation. They're the only one responsible for their actions, not you.)

That would have stung to me too. I would've needed some time to calm myself before I would have been willing to hear that apology. I'm not experienced in polyamory myself, but am familiar with compersion and appreciating joy in someone independent of my experience. It seems hard for her to have initially been able to appreciate your joy and positive past experience. I've done this in real time with relationships when my significant other would have someone purchase them some nice gift that I couldn't get them myself, I would feel threatened for the value I could offer in this way. 'i must not be good if I can't get them the things that make them this kind of happy' it's a hard thing to cope through feelings like you describe here, for you or her. I wish you the best and welcome conversation if you ever need an ear.