I told my guy after I had already decided I getting sleeved. I didn't know where or when it was going to happen, but I had my heart set on it. I had a physical and came home from that sad and depressed. I shared with my BF how miserable I was and how hopeless I felt about doing WW again. He listened to me and said "how about getting a lapland?" his coworker had success with that. I couldn't believe he brought up WLS! I tol him about the sleeve and that I was interested and felt it might be my last hope. I shared my fears about the surgery, my shame about not being able to do this on my own, and the pain I'd be holding in. He finally said, "let's do it!" as if he were having surgery too! I am Si thankful for his support & I appreciate his ability to keep a lid on it as I havent shared this with many others.
My advice is, be honest about your reasons for choosing sleeve. Make him understand how important it is for you. I'm sure he'll support you and your request for privacy. Good luck!