Everyone will let you down at some stage in your life. Everyone. There are no exceptions here. Even the person you are closest to or married to or your best friend will have a moment of self doubt or angst that will prevent them from being 100% genuine or honest with you. Or they will do something they bitterly regret.
Most of the time people will say things they don't mean or think you want to hear. And very often people will take advantage of you and take what they can get from you.
Unless you trust yourself more than anyone or anything you could be setting yourself up for an almighty fall.
Trust who you are and what you represent and be the arbiter of what you believe.