I’m fairly certain the balance the Jedi are supposed to represent is based off of Buddhism. So it’s the balance of body and soul, a balance between extreme indulgence or self-mortification.
Jedi aren’t emotionless, they just aren’t allowed to form attachments. They can still own things, have preferences, have sex, indulge a bit. They aren’t allowed to over indulge. The whole no lover thing is based off of past experience, Jedi taking lovers constantly backfires. Part of the arrogance of Anakin was thinking he’d be different, but he wasn’t.
That’s one of the things I hated about the EU. The constant jedi lovers they had. Kinda reeked of specialness to me, like “look this one loved without problem” when the movies was supposed to show that when one Jedi broke that rule it caused colossal destruction and that the rule existed for a reason. Some Jedi character falling in love and being okay would be fine, but there were just so many.
The Dark Side don’t represent any balance. Indulge as much as you want, or don’t. Love as much as you want, or don’t. There’s no boundries, no balance. They just do what they want, and that feeds the parasitcal nature of the dark side.