First remember the blessing and curse that is existence means that time carries on. So although it sounds trite keep in mind that this too shall pass. Often when faced with hardship it feels like the world is ending, and things will never get better but time can do amazing things with our souls when it comes to finding peace and healing.
Then go for the basics:
Basic #1 - Be like a doctor and "do no harm". When life is hard, it's easy to snap at your partner because of how you're feeling. Instead practice silence when you feel like lashing out. Or better yet, communicate how your feeling to your partner so that they understand your new found quiet and don't misinterpret it to reflect something about them.
Basic #2 - Be kind to yourself and give yourself some space. Wait, I thought we were talking about how to be a good partner? Well, this is how, take care of yourself in the ways your body needs and you will naturally be kinder and more loving to those around you. Remember we are being basic here, so I am not even talking bubble baths, I'm talking - food, sleep, showers, etc. Things that make you feel more stable and supported, then if you'd like you could do something special for yourself too like a bubble bath, a walk around a park, worship, watching a movie, etc. Eventually work towards doing things that could re-energize your soul.
Basic #3 - Let your mouth mount praises. Whow - what the heck? When life is hard you want praises? YES! Praising your partner is like breathing air into the relationship. Let them know what you appreciate, how you feel about them, how awesome you think they are, and why you continue to love them so very much every day. Be authentic and be encouraging. Now, I know some of you are saying, this is really hard went I don't even wanna get dressed in the morning, and to that I say...yes, yes it is. And you can still do it. Take a moment to remember why you chose them as your partner, and then let those reasons stumble out of your mouth.
So as you peak your head out over the blankets and decide to brave the day, remember that your partner is just that a partner. They can be a great source of support, comfort and joy even when life is hard. Whatever this is, it is something you and your partner can get through T-O-G-E-T-H-E-R. You want a good relationship and a source of support, so make sure that you are following the basics even when it's hard. It may be hard to believe but even in the darkest of hours your relationship can remain a vibrant mainline of security and love. Besides, if you're going to be under covers isn't it more fun to have your partner in there with you?