Waifu isn't really a thing you should be getting into, especially if you need to consider rules and book and various other creepily specific definition. All it was, was you wanted to marry, it's literally in the name.
I never once partook in it. I absolutely hated the idea and everyone seems to think konata from my avatar is my waifu. She's not, she isn't even my favourite character. All she was, was an avatar I used one day after about 4 other terrible avatars on mal and this one I liked so I kept it because everyone started to recognize this avi.
Sure I have favourite characters but I'm not gonna fantasize over fucking them or having them be my wife. They're a fucking character, it's not like she'd marry your ass if she was real anyway. I think it's pretty creepy how it's a one sided marriage.