But Mr Pratama died as he was coming home for the wedding when Lion Air flight JT 610 crashed on 29 October shortly after taking off from Jakarta.
“Even though I feel grief that I cannot describe, I still have to smile for you,” the young woman wrote on Instagram. “I cannot be sad but should be strong like you always told me to be.”
She said that before he’d left for the flight, Mr Pratama had joked that should he not return in time she should take the pictures and send them to him.
The plane was carrying 189 people from Jakarta to Pangkal Pinang; there were no survivors of the crash and the fuselage of the Boeing 737 has not been found yet.
The photographer who took the pictures also posted some of them online, explaining the story behind them.
The couple had known each other since middle school, she wrote, and explained how they had decided on the clothes for the wedding and the photoshoot just a few weeks before the crash.
Mr Pratama was identified by his fingerprints on 6 November – his funeral was held two days later.
“He told her that in case he didn’t come home, Intan should continue with the plan,” Ms Pebriana told BBC Indonesian’s Famega Syavira.
She said Ms Syari had been very strong and had kept her tears in.
“But then she video-called Rio’s mom. After that Intan couldn’t hold them in any more. She said: ‘We were supposed to do this together, there’s supposed to be Rio here.’ And she cried – all of us cried too.”
Mr Pratama, a medical doctor, had been required to attend a seminar in Jakarta and had joked about what his fiancée would do if he was delayed.
“Wear beautiful make-up, ask for a white roses. Take good photos and send them to me.”
There is as yet no indication of what caused the crash but the plane had experienced technical problems related to airspeed and altitude readings on the previous flight.