Sometimes you see those lists of what people consider to be "life skills". If I made such a list, one of the skills would be knowing how to handle a bad mood!
It's so important because, looking back to the early years of my marriage, I realize that maybe half the time that we had some conflict was because myself or my spouse or maybe both of us at the same time were experiencing a bad mood.
It could be anything that triggers it. You hear something unkind someone says when you're at the workplace or the temple. It could be some kind of memory that has brought up a bad feeling. Or maybe the day just isn't going right, you didn't sleep well, or there's some stress or some kind of frustration (Yesterday, I ate something that didn't agree with me and felt so heavy and... blah). And so we get into a bad mood. But worse, we might tend to project it onto our spouse! One might snap at him when asked to help with something, or grumble when we do it.
So it's important not to take a bad mood seriously and know how to deal with it. And the same goes when dealing with our spouse having a bad mood...
Don't take it personally!
Now I can look back at the many times when I did allow his bad mood to affect me, when actually my husband just needed to process a bad mood or vice versa.
As for myself, nowadays I try to just look at it like "Oh I'm experiencing a bad mood" I just need some space to process it, to let it pass and turn it into an opportunity to practice things like patience and self control- especially controlling my tongue- so not to project it!
In other words, this is one of the perks of practicing the bhakti yoga process. We learn to see the forest above the trees, become transcendental to the inevitable happiness and distress each one of us is due. Its the mercy of Srila Prabhupada and Sri Caitanya Mahaprabhu.