Bottles aren't perfect, you still have to sit up to use most of them as they generally need some way to let air in as you pull water out. The bite tube also prevents spills without having to move too much or otherwise disturb your partner with one of those pop-nib bottles that has to suck air back in when you release suction.

If she exists, it seems she has more of a problem with the way it looks than its actual functionality. That is a problem that can be solved as easily as getting a bag that doesn't contrast so much with the existing color scheme. Hilarious to suggest a relationship isn't working out over such a minor aesthetic disagreement though.

Being annoyed by a bag is Sheldon Cooper level