I put my togepi in the box for 2-4 years, and when I took it out, it evolved after gaining one level.It was level 11 after evolution, but I thought they had to be level 16 to max out happiness?
Also, I purposefully tried to make it hate me by making it faint, and leaving it, not curing it's status, feeding it bitter medicine, and stuff, but the stupid thing still loved me enough to evolve...What the heck is going on?
Togepi doesn't have to be level 16 to evolve, it can evolve at any level, so you can theoretically have a Level 2 Togetic/Togekiss.
Furthermore, if you tried to purposely make the Pokemon hate you by making it faint and feeding it bitter medicine, this might have been counteracted by you walking around with it a lot.
Otherwise, this is just a glitch you shouldn't mind, since you have a Togetic!
Here are ways to change Friendship.