S'ariq Marriage Walkthrough
Quick walkthrough on how to make S'ariq your very own cat husband. In short:
1) Complete S'ariq's quest, making sure to pick up Gatka-Dar's journal when you grab the skeleton key.
2) Talk to S'ariq in Whiterun and make him your follower.
3) Mention to S'ariq you found Gatka-Dar's journal
4) If you hand it over, S'ariq will read it and talk to you about it when he's Waiting around some time. After the two of you talk, he'll become a normal marriage option.
5) If you do not hand it over, S'ariq will become a marriage option immediately.