Did you learn to stuff certain emotions when you grew up? Are you still pushing some emotions down? Perhaps you're no longer aware of doing so—it's so natural that you don't even think about it.
Most of us learn to stuff emotions. Sometimes it's the anger, sometimes the sadness. In some families, it's even the joy and happiness.
It doesn't take a knowledge of psychology to picture what can happen after years of stuffing. Simply picture a volcano building up over time and heading for an eruption. Something happens that triggers the release and whoosh, it all comes out. Even when there is no huge eruption, there can be smaller amounts that seep out.
I've seen that in my own life. If I don't feel my emotions as they occur—and then release them—they can come out sideways and do significant harm to me and to people around me. For example, if I sit on my anger rather than choosing to acknowledge it and select a way of expressing it that does no harm, it will come out in some way or another, usually not a good outcome! Perhaps it will show up as irritation toward a loved one that's completely out of proportion to what they have just said or done. Or perhaps it gets stored up until something triggers it and kaboom! Some poor soul gets the whole load.
I'm human and don't always get it right. But I try more often than not to feel the emotion—and then release it. I feel better when I can do that. And I'm much more loving and open to those around me, too. Feel and release.