Well 'just' hearing someones opinion is perfectly fine, often there are unpleasant consequences if you don't agree though or at least that was the case when we were young and guided by adults that needed our agreeing. All grown up ourselves, it is our challenge to remind ourselves that no one can force us to agree anymore and that we are not in danger when we disagree even if it means the other person won't like us for it. If they only liked us for being agreeable, the love didn't go very deep.