Old love carries new love along, gradually fading away but never disappearing altogether.
New love is burdened with the old.
We visit punishments for sins not committed, entertain suspicions for errors that someone else made, and generally hoist all the baggage of every love and loss, every quarrel, every joy and sorrow on someone who didn't do any of it. They, of course, do just the same to us. There's no way we can separate ourselves from our past, no way we can avoid staining the clear waters of the future with murky events that happened on another time line, with another person, with a different self entirely. If we're not careful, this wreckage of lost lives and lost loves can drag us down and spoil our chances. Then we retire from the lists of love, bitter and angry, to suck our paws in solitary misery, and hibernate through the endless winter.