Most intimacy apps are either a list you scroll once and forget, or a tracker that wants an account and your data first.
Lotus Love is a private journal and idea library for couples: 500+ positions, a shared "want to try" list, and session planning where the Apple Watch keeps time and tracks pace and heart rate per segment.
It collects nothing - no account, no email, no analytics. Data stays on your device and syncs via your own iCloud, so I can't read a single entry. 7 languages. 17+.