Song interpretation:

She kept talking about good memories from the past, but her boyfriend / husband / lover / partner is still there, they're not apart. A condition where he is there but not really there; I imagine it is a comatose or at least some serious illness where he can't freely move around. " In the gentle flow of time, even the sadness has faded away " as she start to accept the condition : " Not demanding too much, just keep living on. I'm already satistifed with that " . Then she only emphasize it further when she said: " I will protect you in the days to come " , " Whatever happens in your path, I will light your way " , " I will never let go of your hand no matter how long it takes " : she will keep take care of him and won't abandon him until " one day...our hearts will unite as one " .