I'm sure we've all heard this question before when somebody notices we are upset. But is anything really wrong? Just because we are upset by something doesn't mean that emotion is technically wrong. We have to accept and acknowledge all of our emotions. If we never suffered, how could we learn some important life-lessons?
Also, the phrase "What's wrong?" can invalidate another's emotion. Try to be mindful of what the other is feeling and suffering from. Most of the time there is a reason they are suffering which we could possibly learn from or offer our compassion and mindfulness to the matter to help them heal.
By accepting, acknowledging, and being mindful our unpleasant emotions, it helps us heal them faster. We recognize the cause of the suffering, and the remedy. I like to think of our joy as a flowing stream.
Why be unhappy if you can change the problem? What's the use of being unhappy if you cannot change the problem? Accept it, fix it if you can, and return to being.
Thich Nhat Hanh states in The Heart of the Buddha's Teaching that, "Our feelings are formations, impermanent and without substance. We learn not to identify ourselves with our feelings, not to consider them as a self, not to seek refuge in them, not to die because of them." Clinging to our emotions is a high risk action. It can elevate our suffering when we don't have joy, or by letting our unpleasant emotions fester by not letting them pass.
So is something wrong when you are upset? Or is it just the course of things? Nothing is technically wrong, it just is, and we need to accept that.