I hate to admit it, but that last part was utterly beautiful in a bittersweet, melancholic sort of way.
"[I]f they don't let [...] go," is the condition for an irrepairable relationship. If they did let go, there could be hope.
An adage: old chapters close and new ones open. I agree, Chase and Leo could never return to the good old days; the past stays in the past, but by no means is nostalgia "fake". They did have a history, and they could create a future together if they remember said good old days AND commit to changes that improves their relationship. Open communication and willingness to be vulnerable are keys to their closed doors.