We saved all the photos from airline bookings, boarding passes, Aribnb, hotel and restaurant reservations to first meeting photos and so on and so forth. We arranged them chronologically - dated with locations and name of other people on that photo if there's any.
We also took screenshots of our first convo (2-3 screenshots), the most recent (2-3) and some that mentions love, building life together, marriage plans etc (3-6) . The "Search" function on each social media helped a lot lol We also took 3-6 video call screenshots (3) and 2 screenshots of our Whatsapp call logs, even receipts of gifts and remittances (if there's any) ---- everything in a word document then printed them.