My partner wants a period app to replace condoms. How do we discuss the risk?

My partner showed me a green square on a period-tracking app and said, "It says today is fine."

We are still using condoms. I have been looking for information about non-hormonal contraception because I want to discuss my options with a clinician. He thinks that means we have already chosen the app.

So far I have entered three period dates. I have not been taught a fertility-awareness method or checked what this particular app is designed to do. [NHS guidance describes daily observations and training for fertility awareness, and does not officially recommend tracking apps](https://www.nhs.uk/contraception/methods-of-contraception/natural-family-planning/).

When I said a green square was not enough for me, he asked whether I trusted him. I do trust that he wants this to work. I am not willing to treat that as an answer about contraception.

What would a shared decision look like when one person wants a simpler routine and the other would bear a pregnancy they are trying to avoid?