"Not that anyone should care, but in order to not give the press the chance to invent crazy and hurtfull [sic] drama, I prefer to tell my fans personally that Nick and I have decided to be apart," the Modern Family star wrote in a message posted to her WhoSay account.
"We have being having too many problems with figuring out how to spend time together and becouse [sic] of my work and now his, its been getting worse and worse, not fun anymore. We are still very close but we belive [sic] is the best thing for us right now," she added.
Loeb, 38, and Vergara, 41, started dating back in 2010. They reconciled after a brief split in 2012 and Loeb proposed soon afterward at her 40th birthday party celebration in Mexico.
Vergara told Cosmopolitan in 2013 that she hadn't started planning her wedding because of the large party she threw herself in Mexico.
"When he proposed, it was my birthday, and I'd flown more than 100 family and friends to Mexico for six days of partying. It took me forever to arrange the logistics! If I had known I was going to get engaged, I don't do this stupid birthday," she said at the time.
Vergara spent Memorial Day weekend in New Orleans with family.