My current one is six years younger.

Last one was five years younger.

I think, subconsciously, it's because I never got anywhere with anyone when I was a teenager so not only would having a younger girlfriend be a bit of an ego boost, it would almost heal some scars left in me from those days.

Nah.
Age is not relevant for me.

Four have been within a year of me, the last one was 5 years younger. I met her through a college class and thus assumed she was only a couple years younger than me, but it turns out she was taking it as a supplement to her high school classes.

Mine is seven months older than me, actually

They have all been around my age within a year but that is because they have all been from my place of education, school or Uni. Also I am still young yet but perhaps when I am older I might like younger women than me. That's an interesting theory you have about it.

My two game changers were each three years older, apiece. I tend to be into older women, but I am sure I could find a oneitis who is younger as well, provided she is cool.

My oneitis is 23 year old - so six years younger than me. Her boyfriend is almost 26.

Yes. And as I have gotten older, new oneitii have stated around the same age. Early to mid 20's. Since I am now too old for that to be realistic, I no longer suffer from oneitis. Yay something good coming from aging!

Both have been 1 year younger than me.

I suppose (just a random theory, I have nothing to back it up) age has a lot to do with the imaginary relationship dynamic that tends to come with oneitis. With a much younger girl, fantasies would be more oriented around protecting her and showing her the world. With an older girl, you imagine she'd provide the nurturing you never had or something like that.

In my case (oneitis roughly the same age as me) I fantasized about being activity partners, doing stuff together. The second one was actually my girlfriend, but I had (and still have) a completely different imaginary relationship going on in my head, and I couldn't make the real one work as well as the imaginary one.

all but one have been older.

If I were to consider some women as oneitises (which would be stretching it too much), then one a few months older and one a few years younger. No trend there...

I'd agree with that. I tend to find that the type of girls that become a oneitis for me have a certain sweetness and naivety. Almost being like a daddy to her.

Interesting. Mine tend to be the other way around. Maternal, more worldly and sociable types who would be like a manager, or mother for me. This apparently appeals to an Aspie man, as he knows he'll probably always need someone to help organise himself and to look after him.

I can certainly see the appeal (I'm an Aspie as well) but the daddy thing is nicer to me. Maybe it's to prove to myself that I can be organised and have responsibilities.

You can probably guess that I'm thinking out loud by this point.

I try not to think too much of it but yeah, They tend to be younger. I'm constantly asking myself if there's something wrong with the way I look at things.