Probable Predictors of Involuntary Singlehood
sciencedirect.com
sciencedirect.com
They also found that self-perception of some variables matters, but having not read the entire paper, it’s not clear if they attempted to measure external perception of the same variables. I’m guessing they didn’t, since BMI also is quoted as a factor.
Other things strike me as blindingly obvious: e.g. being choosier leads to being single longer. I’d argue that’s pretty much true by definition.