Things aren’t going to go exactly the way you want them to. Because things aren’t supposed to go the way you want them to.
Most things are actually inclined to fall apart. It’s generally much easier to break something than it is to fix something. You have to work hard to build things, but it’s usually easier to tear things down. Etc.
This isn’t only true in a scientific sense, it’s also true in our relationships.
That’s just the way this world is. So we have to learn to live with it.
Be adaptable, and be grateful for the things that do go your way.