It is not a nice feeling when someone forgets all you’ve done for him/her. As a dad, I get hurt when my girls sometimes forget all that I have done for them over the years. At those moments, I think to myself, “How can you say that after all that I have done for you?” 
Have you hurt God like that? 
The Israelites did (hurt God) in the wilderness. When they were on the outskirt of the promised land, they sent out spies to survey the land, and this is the conclusion they drew: “Why is the Lord bringing us into this land, to fall by the sword? Our wives and our little ones will become a prey. Would it not be better for us to back to Egypt?” Numbers 14:3
And here is God’s response: “How long will this people despise me? And how long will they not believe in me, in spite of all the signs that I have done among them?” Numbers 14:11
When we doubt God’s goodness because of our circumstances and misfortunes, we are hurting God. 
“He who did not spare his own Son but gave him up for us all, how will he not also with him graciously give us all things?” Romans 8:32
Why did Paul have to say this? Because he knew there will be moments and circumstances in our lives when we would be tempted to doubt God’s good intentions for us. 
Trust His goodness for you.