If anyone ever had a reason to become bitter, it was Joseph. His brothers plotted to kill him but instead sold him as a slave. He was falsely accused of immorality and imprisoned for it. Though Joseph showed kindness to others, like the cupbearer, they promptly forgot him when they had opportunity to show him kindness. He was left in prison for two years to deal with his disappointment.
Ultimately everyone is totally dependant on God for all their needs. If you look for deliverance and/or salvation through a person, any person, you will be disappointed.
When others disappoint us, we should follow Joseph’s example, and look to God who is always faithful and dependable and capable of meeting all our needs in any situation. He may take his time as in Joseph’s case, who waited for 2 years. The secret is he waited for God. His hope was in the Lord.
Isaiah says it well, “even youths grow tired and weary, and young men stumble and fall; but those who hope in the Lord will renew their strength. They will soar on wings like eagles; they will run and not grow weary, they will walk and not faint.” (40:30-31)