I think I actually find this a lot less depressing than the "I'll love you until my death" stories. They make it sound all poetic and romantic, but from Remilia's POV it's like falling in love with a one-night-stand or something... it's nice at the time but in a few thousand years it'll just be a faint, vaguely endearing memory, overshadowed by all of her other lovers and/or by the actual love of her life. Makes the whole thing seem a bit pointless!