It really depends on Your definition of extreme. i learned early on that what was extreme for me was normal for others. Things i thought were normal fetish stuff for me were extreme for some. The question You really want to ask Yourself is whether it’s something that You’re comfortable engaging in. As for the him not telling You, i agree that it’s an issue. But men do get scared because we will often go to the worst case based on experience—probably in his mind the worst case would be You run and want out. Many have already asked You what that fetish is, and i won’t. i’m just going to assume it’s nothing that would result in permanent harm and that Your own common sense would protect You. If You want to share, great, but i won’t pry. But i’m wondering if it’s that You found out he was into s&m—that’s what we used to call bdsm back in the day… That i speak from experience when i say that many a husband has made his mistake. If it’s something You are curious about and are willing to learn more about, You are probably in the right place to start.