Cuckold

Shikamaru wanted to try being cucked, or rather he just wanted to watch Temari get's ruined by another man, she wasn't that into it but she had agreed to try it after a lot of begging.

His only real criteria for what man to choose is they had to be considerably longer then his own 7 inches, and trustworthy enough to not like kill Temari or anything like that.

And Shikamaru had the perfect guy in mind.