Which are constant in the world?

Buddy change is the only constant. I'll tell you why. Nothing 'Still' can survive in this world. Even rock, mountains are subject to movement and change.

It is my belief love is the only constant in the world. Not love to a singular person or thing. That will also evolve. But greater love can never perish.

One could never just stay still. He/She will deteriorate and die. If one held on to one thing too much then that is death too. That thing will wear out, change or morph.

Interaction, movement and love can be relied on constantly. If however your question is in reference to a scenario then do elaborate.