Frenemy

"Frenemy" (less commonly spelled "frienemy") is an oxymoron and a portmanteau of "friend" and "enemy" that refers to "a person with whom one is friendly, despite a fundamental dislike or rivalry" or "a person who combines the characteristics of a friend and an enemy." The term is used to describe personal, geopolitical and commercial relationships both among individuals and groups or institutions. The word has appeared in print as early as 1953 in an article titled "Howz about calling the Russians our Frienemies?" by the American gossip columnist Walter Winchel in the Nevada State Journal.

A Businessweek article stated that frenemies in the workplace are common, due to increasingly informal environments and the "abundance of very close, intertwined relationships that bridge people's professional and personal lives ... [while] it certainly wasn't unheard of for people to socialize with colleagues in the past, the sheer amount of time that people spend at work now has left a lot of people with less time and inclination to develop friendships outside of the office."

...
Wikipedia