Because she didn’t give you permission to hit her. Simple as that.

yea sorry if I smacked my wife’s ass and that resulted with a black eye either I get to hit you back or that’s the end of the relationship

is she bi polar? that's definitely a mixed message. also, a bruised eye when she asked for it to begin with is overkill. (I'm a girl btw)

Depends on about a million factors. 1) did she ask for it? 2) Was she expecting it (see 1). as in was it total surprise? 3) how hard you smacked her 4) where you smacked her bottom. 5) were you in public? I feel these should be your starting queations... I think the surprise factor was a huge factor and you likely did it in a way and location (on her) that she didn't enjoy. just my first thoughts.

dont ever smack asses unless directly asked, and do so only when asked.

never mind, there are so many other asses to smack in this world.

see, there's this thing called consent. she consented to you smacking her ass the other day. she didn't consent to you smacking her ass this time

Her giving you a black eye is domestic violence. There is no excuse for her to hit you. I am sorry that happened and hope you are okay.