The couple quietly began dating in 2010, but it emerged the pair had since called time on its relationship last month (Aug14).
Mellencamp, who lives in Indiana, has now opened up about the split, revealing the long-distance romance proved to be too much of a challenge.
However, the musician admits he still thinks highly of Ryan, who is based in New York.
During an interview with U.S. shock jock Howard Stern, he said, "Meg is an angel. She was just an angel sent to me at the right time. We tried to have a relationship for three years - long distance. We'll see what happens."
The 62 year old then joked about what he's looking for in his next girlfriend, quipping, "I need, like, a nursemaid - a wet maid or something!"
Mellencamp previously revealed to Rolling Stone that he had no intention of moving to the Big Apple to be closer to Ryan, admitting, "I'm too sensitive to live there (in New York). I can't see poor people. I can't see the suffering. I can't see the trash on the streets. I'm not leaving Indiana. I'm going to die here."