My gf has an 07 Aura, and when she turns her highbeams on, her lows turn off. She said this wasn’t always the case, and her lows sometimes still stay on. I recently replaced her low bulbs and didn’t see any wire chaffing, so could this potentially be a fuse or relay issue?

 

The current operation is how it came from the factory (or should have anyway. A previous owner may have messed with it to have them stay on with the highs but in this day and age of headlight bulbs and not sealed lamps, it's pretty much blinding to oncoming motorists to have them both on at the same time.

The same behavior can be seen for fog lamps, which will go off when you kick in the high beams.