A significant other whose status is not created by a agreed-upon relationship status but by how much time is spent with them. Could also be considered a behavioral significant other.

Combination of "statistically significant" and "significant other."
Since he spent twice as much time with Karen as with any of the other girls he was dating, his friends called Karen his statistically significant other.
by Brett Lider February 5, 2009
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enough ex-boyfriends/girlfriends to constitute a valid scientific study (more than 30).
You'd better stay away from Pamela; she's got statistically significant others.
by Robert Stephenson April 6, 2006
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