People Change
People change everyday, even if they attempt to try to stay the same. They physically become older. They are mentally exposed to ideas that will shift their thinking, even if ever so minutely. They are emotionally touched by new kindnesses and cruelties perpetually, shaping and reshaping their hearts. They are spiritually challenged and rewarded. Change is the one constant every individual does experience.
Most change is subtle. Yet, everyone also experiences moments of instant upheaval, which brings more sudden and swift changes. A car crash, a lost job, a son given a death sentence before he was even born. A marriage, a promotion, the holding of your newborn daughter. How can one not change under such drastic events?
However, your question perhaps implies this question instead:
"Do you think that people have the will to change?"
A subtle difference, and yet the answer is the same.
Can the man in the car crash, that happen to lose one of his legs, change? Can he find the will to change from someone that use to walk but currently cannot, into someone that will walk again?
Can the newlyweds change from being individuals into being more of a unit. Can they make the sacrifices to each other to make the marriage withstand all of the forces that will try to diminish it?
Can the person you love change...
...change the self-destructive behavior that is slowly killing them?
...change the traits you cannot stand to make it easier to take the next step?
...change whatever you are hoping they can change to make yourself feel better about them?
The question can then become more reflective...
"How much change are you willing to do yourself for another? What are the things you are willing to change and what are the things that are off the table? And the scariest question of all. What are the things you would love to change, but are too weak/scared/etc. to do so?"
When you can answer the above honestly to yourself, and then mentally ask the same about the person you are wishing would change, you may get closer to the answer you are probably looking for...