Love is... an opening. In a sense, an invitation to embrace exactly what is; to embrace someone for precisely what they are at any given moment. Most other forms of love strike me as "transactional," and then it stops being love at ALL... as you alluded to... I will love you for as long as what you do pleases me, but when that stops I no longer love you.
Love without limits and conditions is rare, though. People find something-- a connection-- and cling to it like it is a "thing" or something you can own. You can't.
Love simply IS. And more often than not, it is also the answer.
'I love you' is too often said as passive aggressive possessive. If one takes ownership, one fears to lose it that fear encourages manipulation and resentment. How can it be love?