Ask HN: NSA-resistant mobile sexting apps?

I'm a minor hacktivist and may be on a few watch lists. Very soon my partner and I will spend some time apart. What mobile applications are there for sending multimedia messages (photos, videos, text) on mobile platforms that provide at least some assurance of data expiry / privacy than say whatsapp or path provide?

We are on a mobile platforms that run some closed source code so we understand that we will not be able to obtain NSA-proof sexting. Hence, "NSA-resistant".