I always find it amazing how men suddenly 'can't remember' things that they know would cause their partner a huge amount of distress.
They can never remember things as significant as getting a hickey (or kissing someone, or sleeping with someone).
Funny how its always these big, massive, flashing red light moments that they can never remember the details of. Always trotted out as "I can't quite remember, I must have been soooooooooo drunk. But I remember what I DIDN'T do, and I remember Mick had the chicken wings that night and I got a cab home with Ben and Jerry, so all is good. Its just that massive significant moment that would make you mad at me that has slipped right out of brain".
It must be horrendous forgetting these things which could clear all the heartache up in a moment, as you know, because they couldn't possibly have done the thing you are thinking they have definitely done.
Poor loves. Imagine living with that type of amnesia.
I'm going to hazard a guess though....
He remembers very fucking clearly how he got it.
He just does not want to tell you.
I'm sorry. Another shit man exposed.
Even without the hickey he has paid to be face deep in another womans fanny. I imagine if you asked him about that he wouldn't be able to 'remember' all the sordid details of that either. Just the bits he thinks he can get away with telling you about.