Perez began the season impressively, but was offloaded by the Catalans on-loan before Roma took up the permanent option before expected.
He told AS: "To this day I still do not understand what happened. Either the club needed money or there is something else that escapes me.
"But it is already past. At the time it did worry me because it is tough to leave Barça and stop seeing your family and friends. Since then from my close surroundings I have only seen my parents.
"I always told my mother when I was at the club that I didn't know what I would do when I had to leave Barça. Many people explain that it is very cold outside of Barça, but I consider that there is a lot of life outside of Barça. I am very good in Rome and I am earning a place."