Almost all my encounters with ultra-length hair happened with a woman who at that moment was unaccompanied, or with a gjrlfriend.

I have never met anybody who recognizably had the same fetish as me, and it´s definitely not enough to qualify for the fetish by having a partner with extremely long hair.

Many years ago a show on German TV dealt with all sorts of hair (short, long, colourful, baldness, you name it). It also featured Marianne (of Amazing Hair) and her boyfriend who appeared to be totally uninterested in her spectacular hair. But as even in these few minutes she came across as a very nice, sensible, intelligent, reliable, and very attractive woman even if you left her hair aside, he may have been thoroughly attracted by her for many other good reasons.

I think a better way of determining someone with a hair fetish is to watch his reaction to chance encounters. He many pause and turn around to see women from behind who had just passed him walking the other way, with him now trying to assess the length and quality of their hair when from the front he could only see that it was past her shoulders, but as she kept it tucked behind her shoulders, the view from the back was his only chance to catch a real glimpse.

I think that such a reaction or a similar strategy of trying to catch as much of the sight of long hair as possible in daily life would be more reliable signs.