Ryan's engagement news comes after she was pictured out and about flashing a diamond ring on that finger, fuelling rumours she was either about to tie the knot or had already walked down the aisle with Mellencamp.
"ENGAGED!" is what she wrote. They became a couple as his marriage to Elaine Irwin was ending, although it hasn't been without problems. He and Ryan started dating in 2010 and broke up five years later. "She hates me to death".
"I was a journalism major at school and a curious person, and I wanted to go back out into the world and figure out who I was - am - in relationship to other things and other people and other environments", Ryan says. I throw fits, I gripe, I complain.
President Trump insults reporters, claims Jim Acosta video 'wasn't doctored'
Other social media users are sharing one of Mr Trump's tweets from 2013 where he criticises the "intimidation of its reporters". The New York Times also noted that Acosta's monologues have led "some of his rival White House reporters" to roll their eyes.
In July, a source told ET that the two were together again.
The When Harry Met Sally star was previously married to Dennis Quaid, and for a while, they were considered one of Hollywood's most beloved couples. They share a 26-year-old son, Jack, who starred on HBO's short-lived drama, Vinyl. She was married to Dennis Quaid for nine years and had one son with him, Jack Quaid.
Throwback: Ryan's union to Mellencamp will mark her second marriage.