"Frenemy" is a portmanteau of "friend" and "enemy

Enemy

An enemy or foe is a being that is seen as forcefully adverse or threatening. The term is usually used within the greater context of war, to denote an opposing group as a threat.Enemy or Enemies may refer to:-Literature:...

" that can refer to either an enemy disguised as a friend or to a partner who is simultaneously a competitor and rival. 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.
A Businessweek

BusinessWeek

Bloomberg Businessweek, commonly and formerly known as BusinessWeek, is a weekly business magazine published by Bloomberg L.P. It is currently headquartered in New York City.- History :...

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 ...