When you rely on someone you're expecting them to be there and to do what they said they would do. You move forward believing they will be there. You count on something happening.
I'm sure we all have stories of relying on someone and they didn't come through the way we expected. We know the disappointment of someone proving to be unreliable.
When I was reading in 1 John recently, I was struck by the words in one of the verses.
1 John 4:16 says:
"And so we know and rely on the love God has for us. God is love."
In this verse, John is telling us that not only can we have knowledge God loves us, we can rely on it. We can rest our entire lives on the truth that God loves us and He will never prove unreliable.
This verse goes on to tell us God is love.Because of that we can rely on God's love for us. We will never be disappointed or find it's not there.