There are truths so unpleasant that we chose to ignore them. There are truths so apparent that we simply overlook them.
Life is difficult; humans a fragile and suffering is inevitable. This is the most unpleasant truth we chose to ignore, or even to deny.
Everything, good and bad, passes and is soon forgotten—this such an obvious truth we simply overlook.
Why are we so confident in good times and so ignorant in bad times? The knowledge we need is out there for centuries and for free. All we need to do is browse the history, scan the headlines of the news and look around. And think.
And probably, we should have paid a little bit more attention to the philosophy course. Then we would know better that:
We can not always be happy nor continuously sad. And this is because everything passes, and this will also pass.