1stly before we can answer the OP's question, we must define
what is love. What is love?
Is it a warm feeling? Does it occur during sex? Or only when you
are happy? When things are perfect and going well between both
parties?
I only see 'love' when everything is going wrong and the other
party still doggedly sticks to the other party. I think synomynous
with love is 'perseverance'.
You can't quantify and observe love when everything is perfect. You
see, I think love is a choice. It is when you make the decision and
choose to stay with someone despite all shortcomings.
Love comes when you don't want to go through with a situation, and
yet you choose to do so because of the other party.
PS: I think the words 'for better or worse' sums it all up.