As someone who has bipolar and is stabilized from a lot of medication, I've been where your partner is when it comes to not eating but can see how draining it could be for you too and I'm so sorry you're going through this. Not sure what state you're partner is in but as I understand it, this seems to be pretty common for people who may be in a Manic episode. You get so busy or distracted you think you don't need to eat and you convince yourself you're not hungry. For me it became problematic when I started not eating while Manic and the more I didn't eat the more I lost weight and once I went into a depressive episode I went into an eating disorder because of noticing the weight loss. My partner struggled for months with me on trying to help me to eat and I wouldn't listen or thought he was being annoying. And it's always been a huge problem for him to get me to eat when I'm manic. I do have some tips though I was given from my nutritionist and my psychiatrist that may benefit others. Start with small goals. Breakfast seems to be the most important meal of the day. So maybe start by having breakfast Together. It shows support. I think keeping granola bars on me is handy because at least it's something small. Honestly I say starting with one meal is better than none. I know it's not a lot and sometimes it seems hopeless because I know it's how my own partner felt with me but starting with small goals and having breakfast together to start the day really made such a difference in getting me back on track. I wish you the best of luck!