I'm sorry your partner is having a relapse and is struggling, that must be very hard for you both. I'm happy to help you find whatever information and support you need.
Here are my suggestions first off. If you were looking for something else, just let me know and I'll help you find what you need.
First off, I'd want to make sure that the reasons for the relapse of the psychosis are addressed. Relapses can be caused by changes in stress, life situation, not taking the correct doses of medication regularly, changes in other medications or recreational substances (cigarettes, alcohol or other drugs for example), hormones and other changes in health. It can take awhile for medication to 'wash out' of the system, so it might seem fine to her to reduce medication at first but over time symptoms will return. Reductions or changes in medications should never be done without a doctors instructions. It can also take awhile for the right medication or combination of medication to be sorted out, as everyone's brain is a little different, so the doctor may wish to change her medication if it's not dealing with her psychosis symptoms or depression very well right now.
Active psychosis is really hard on the brain, and can cause problems that take time to heal up afterward. It's really urgent that symptom be treated asap. If this is already being addressed by her psychiatrist and she's taking the full dose of all her medications, then I'd move on to other things (see below). After her psychosis symptoms are on the wane, it will take awhile for her brain to heal and her health to gradually improve.
Here is a fact sheet on general ways to support a person in recovery from psychosis (once they are receiving optimal medical treatment). http://www.bcss.org/resources/topics-by ... -recovery/
Basically supporting recovery is supporting health. Both depression and psychosis take a big toll on people's ability to focus mentally and to maintain their physical health, which includes and influences their brain health. Things like good quality rest and sleep, exercise and eating well have a bigger effect than you'd think, and as her partner you can help make those things happen. Psychosis is confusing, so a quiet, low key environment really helps too. Omega 3 fatty acids (dose for persons with a brain illness is about 2 grams a day, which is more than you'd get from eating a lot of fish, it's about 6 fish oil capsules a day) has scientific studies supporting it being helpful in maintaining brain health for people with depression and psychosis, and vitamin D supplementation daily is also helpful. Even things like handing her her medication and supplements daily to help her remember to take them, keeping cut up fruit and veggies and hard boiled eggs in the fridge to make healthy snacking easier, and going for walks with her or to the gym can help a lot over time. Regular exercise, particular vigourous exercise, also has a lot of supporting studies showing it has positive effects on depression and anxiety, so again, helping her establish those patterns can really help. It's hard to get motivated to do this on your own when you're depressed, so having a loved one provide the structure and encouragement to make it happen is very helpful and will probably help with your own stress.
You are very welcome to share whatever challenges you have as a partner here or in the other online support groups on this forum. There are also some family support groups in Vancouver (and around the province) that might be helpful. If you encounter any issues relating to being a same sex couple (I don't expect any) or have any concerns at all, please contact me and I would be happy to talk to the people involved. I'm a lesbian myself and know people at most of the organizations involved. Here's a listing of family support groups in BC (these would be for you): http://www.bcss.org/monthly-meetings-calendar/
The mood disorders association has self-help support groups for persons with depression that might be helpful support for your partner. Here's their contact information: http://www.mdabc.net/peer-support-action-groups