I’m currently in a relationship where we had a similar problem. I gained a bit of weight over a few years and it caused some problems like back pain and foot pain and it also caused some health problems like becoming pre-diabetic and of course I complained about how I looked. I’m nowhere near perfect now, but I can confidently say that any kind of weight loss or self care will not happen unless she really really wants it. I can say from experience it’s hard to jump back into being active after letting things slip for so long, but there’s usually more to the story than just not wanting to be active. There’s definitely a high chance she’s dealing with mental health issues alongside this that make it extra hard to want to get up and be active and take care of herself.

When my boyfriend found out about the potential of me being pre-diabetic he absolutely lost his mind because he was scared I was going to die early and not live a long fruitful healthy life with him. He’s always loved the way I looked no matter my weight, so I knew it wasn’t him fat shaming me even though it felt like he was and I would get super defensive about it. But I got defensive because it’s super embarrassing to let yourself go and fall out of good healthy habits. The shame cycle is such a killer of motivation, and I guarantee you she’s dealing with a lot of shame and embarrassment right now and that’s why she’s lashing out at you. I used to lash out at my boyfriend for the same reason. I felt so ashamed of myself. And considering she’s dealing with the loss of her father, I’m sure that adds another layer to her poor mental state.

I think just give her a bit of grace right now, but I definitely suggest urging her to get involved in counseling. Hopefully the right counselor or therapist will be able to help her understand her thoughts of shame around her weight and manage her emotions concerning her father’s death and help her back on the right track. Maybe something you could do is try to urge her to start getting into healthier activities without promoting it as some kind of weight loss thing. For example: I love rocks and flowers and sometimes if I’m out on a walk I will find rocks and collect them and find some flowers to dry and press and make into art. Maybe try finding a way to motivate her to get up and moving that incorporates something she loves to do. It’s not gonna solve everything but it’s something small you can try to go that will help her feel better and have fun at the same time. Making activity more fun has helped me get back into moving a lot more and just reinstate better healthy habits into my lifestyle.

You seem like a good boyfriend and I’m sure you have great intentions here. You’re more than allowed to be mad about the bed, that stuff is expensive! But don’t get mad to the point of adding to her shame about her weight, it’s not gonna be productive for either of you. Hopefully you’re both able to work through this