With proper insertion, neither you nor your partner should be able to feel the disc. If you can feel the disc, you may need to try readjusting your disc as there may be an issue with the placement of it.
You may also need to try a different position. The best position for your partner to avoid feeling FLEX during sex is either missionary or doggy style. Once you get in the groove of things you can mix it up.
If you're still experiencing issues, please reach out to us at firstname.lastname@example.org we're always happy to chat about tips for making the discs work for you!