Love that pours

An analogy to better this verse would be how we show love to others, represented with a jug of water.

When someone shows love for us we pour lots of love back on them, like pouring out water from a jug. When someone fails to show us love we hold back on pouring out as much love and even stop pouring out love at all. This love is wavering and is not constant and very limited because we can also stop pouring out love when we run out of it.

However, God's love is not like ours. Instead, it is ever-flowing and always constant, never stopping, and never depending on how we act towards God. 

This is what it means to have unfailing love. Isaiah talks about the unfailing love being more reliable and stronger than the mountains, which have stood in their place indefinitely.

We are nowhere close, but this is what we aim to see when we inhabit the Holy Spirit, a love unwavering and independent of the circumstances around us.