I love reading the book of Psalm and one of my favorite chapters to read and listen to is Psalm 118. I usually read NASB version and it states repeatedly that "His lovingkindness is everlasting". It wasn't until I started listening to an ESV audible version of the Bible that the 'steadfast love' started to resonate through me. I prefer "His steadfast love endures forever". This is mentioned 5 times during the chapter. Essentially the two translations mean the same but something about 'steadfast' that allows how much God loves us and how deep that love is.
The meaning of steadfast is defined as
1. firmly fixed in place: IMMOVABLE
2. not subject to change
3. firm in belief; determination or adherence: LOYAL
Applying the definition of steadfast to God's love. This means no one and nothing can remove God's love (immovable). His love will stay the same no matter if our love changes/lessens towards Him. Nothing we do will change His love towards us. God's love is always present because he believes in us (loyal).
Take some time to read Psalm 118 and if you can, use an ESV version but any version will suffice. Just realize the wording will be different but the meaning is still there. God's love is eternal. God's love is never ending. God's love is consistent. God's love is perfect!