That's pretty cool! The music and video have a neat sci-fi aesthetic to them; they make me think of Daft Punk or Blade Runner. Which is kind of cool with a love/relationship song. What's the high-pitched main instrument you use for the instrumental? (I'm always curious about where people get sounds for more electronic music like that that don't seem to come from traditional instruments.)
If you wanted to pick at anything, you might tweak the phonemes a little in some places. For example, that first "tonight" is being pronounced something like "tuh-night." It's definitely not wrong, but I'd guess that most people would have difficulty saying the word like that. Unless it's what you want, and provided you can get Gumi to do it (Though you've got her doing a really good job, I think, so it seems likely possible.), you might want to adjust her phonemes so she says "too-night." You might do the same thing for "tomorrow" at 1:34, but that's probably even more a matter of preference.