This is my view of the Jewish view, for what it is worth.
Unrequited love is a test: nothing more and and nothing less. It is a test of whether we still love G-d and believe in His goodness even when He seems to deny us something precious to us.
To lose love -- to lose anything or anyone that lit up our soul, that resonated with us so individually as to affirm who we were -- demands a hard reckoning with the meaning of our lives. As at each of the times in life when we lose important things, we are weakened and evacuated. We are sobered to the point of shame. We are sent to the trenches and forced to recalculate, to reappraise.
There, in the trenches, we meet G-d. And we confront, as after the death of a loved one, the mutability of absolutely everything--a most terrifying, most lonely truth. Eventually we learn slow, important, eternal things -- that the refuah preceded the disease and will supersede it; that the Source of what we lost is bigger than what we lost, and can and will yield more of the same light, and will do so abundantly and visibly for us and those we love, for long years.
And so we decide to live on. Life feels as if it begins again, that we must start over with nothing. But we do and we do bravely. The Holy One, Blessed be He, takes pleasure in our effort to find more life and more light in life, and more of the hidden holy Light that is in fact still everywhere. He answers, at that moment, with a silent promise to take away our pain. At that moment we pass the test.