It can be tough enough dealing with stress in your own life. If you're part of a couple, though, things can get even more challenging. So much depends on your partner's style in handling (or not handling) stress.
Does he get loud, or does he become very quiet? Does she get reckless, or retreat into the couch or her bed or a book? Does he want to talk about what's on his mind, or does he want to take out his tensions on you?
It might help to remind yourself that while your partner is dealing with some stressors right now, if you are not, then you don't have to be stressed out. It's good to be aware, and stay aware, that your partner's stress does not have to become yours.
You can sympathize, and try to make life a bit easier for him, without taking the burden onto yourself.
Think of what you'd want from a nurse. A nurse is not helping patients by sitting down and crying with them, or by becoming overwhelmed with the crisis or illness they are overwhelmed by.
No, you want nurses who are sympathetic but detached. They are not being crushed, they are on top of things. This can be very comforting and reassuring to someone whose body is betraying them.
In a similar way, you are probably more helpful to your partner if you are not empathizing to the point of becoming one with his fears and anxieties.
So maybe it's a good idea to resist the idea of indulging, or babying or weeping with your partner. You could end up making her feel worse. Maybe, she may wonder, maybe it really IS as bad as she thought it was.
Do not hover, offering to do things, to bring things, unendingly asking, "How are you now? How about now?"
This is my natural tendency and I assure you, it doesn't work.
You don't want to go to the other extreme though, either. This is not the time to look her in the eye and demand that she fly right and get her act together. Not the time for the white-glove treatment on the woodwork and furniture. Not unless you want tears, slamming doors or an argument.
Want to offer to make dinner though you don't normally do so? That might be very nice. But don't feel like you must carry your partner's usual load.