Everybody is different. The reason I need to go to bed early is that I wake up before 7am every day, regardless of when I go to bed. So the only way for me to get 8-9 hours of sleep is to go to bed early.

Your body is different from mine so you need a different routine. My point was that it's important for me to maintain a certain schedule which was incompatible with my partner - which is fair enough.