The sexual equivalent is acevague.
Arovague was possibly coined by deactivated Tumblr user dogora before November 30, 2014.
The arovague flag was designed on or before December 16, 2016 by DeviantArt user transboy-lou. The design was inspired by the gendervague flag. The color meanings are as follows: "The big gray space is supposed to represent the “vagueness”. And there’s also an option to put a different orientation flag in the gray space as a combo."