"His love endures forever" appears to be a victory mantra of the Old Testament. The Israelites entered their battle against the men of Ammon, Moab, and Mount Seir singing:
"Give thanks to the Lord,
For his love endures forever."
They didn't go forward singing, "Give thanks to the Lord, For His power endures forever" although that would have been true, also. Instead, they were praising His unfailing love.
Perhaps God is much like a parent who provides for her child simply out of love--not merely because she has the resources. God provides for us because of His constant love. It is on the basis of this unfailing love that He likes for us to trust Him to answer our prayers.
The Israelites' words were a statement of trust. We are to be confident that what God is doing this moment and every moment is a manifestation of love. It's done solely because we are the objects of His affection. "Your loving kindness never fails" means there is never a moment that He's not expressing loving kindness to us.
How good it is to think of God's power when we pray and to remind Him that He is able to do exceedingly abundantly more than all we ask or imagine. But I think God is even more pleased when we enter our prayer battles remembering His unfailing love.
The words "his love endures forever" assure us that now and always--not just ten years from now, but this moment--God is acting out of love for us and for those for whom we pray.
I can trust You, God, not because of my own righteousness, but solely because of Your loving character.
"Consider the great love of the Lord" (Psalm 107:43).