Now hope does not disappoint, because the love of God has been poured out in our hearts by the Holy Spirit who was given to us. (Romans 5:5)
Paul has been explaining the blessings that belong to those who have been justified. Those blessings include:
Having peace with God.
Standing in the grace of God.
Rejoice in hope of the glory of God.
Glorying in tribulations.
It’s clear that the Christian has everything riding on the promises of God. Paul will remind Christians that their hope does not lead to shame or disappointment.
God will not disappoint us by breaking His promises.
The Christian’s hope doesn’t disappoint.
Paul indicated that Christians will not be disgraced because God will ultimately vindicate His people. This corresponds to many Old Testament texts that refer to people not being shamed or judged because they follow God (see Psalm 22:5; 25:3, 20; 31:1; Isaiah 50:7; 54:4). - Pollard, Truth for Today Commentary, 170
The Christian can continue to glory in their tribulation because, ultimately, it produces hope.
And God will not let us down - our hope is well-placed in the promises of God. No matter what we face, God is greater.
Because of the love of God.
We will not be disappointed or put to shame because of God’s love for us.
Our hope, sustaining us in the present, is also tied up with future expectations. We can rest assured that our future will not end in shattered dreams because God’s powerful love has filled our hearts. The Holy Spirit is the channel by which God’s love has entered our hearts. - Pollard, Truth for Today Commentary, 171
As Paul continues in Romans 5, he will build upon God's love for us.
The justified can rest assured that God will not disappoint us - and we know this because of His great love for us.
God always keeps His promises, and He will not let us down.