Showing Opposing View Points - Screenwriting

Your main character will Want something and have a Reason for wanting it.

Another character will Want something.  It may be the same thing.  It may not.  But they will have an opposing Reason for wanting whatever it is they want.

These Opposing Reasons will be in the context of a relationship problem.

In other words.

If one character argues that the main characters motivation, that their reason is flawed and suggests another goal and reason....allow that second character to go after that goal and prove their reason.