For me, age is irrelevent.
I have aquaitances that are 18 & I have aquaitances that are over 90. Some people at age 20 can be more mature in outlook than most people who are 70. It ALL depends on the individual.
As for a potential partner, I have observed that most people tend to "grow up" around the age of 23, and at about the age of 30 most people tend to "let go of childish things".
For me, the partner would have to be someone aged 23 or older.
As for the oldest age I'd want a potential partner to be, then that once again depends upon the individual concerned. As I'm 39, then maybe it should be about 50.
So my age bracket would be 23 to 50.
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We, the people on the Autistic Spectrum have a choice.
We can either try to "fit in" with the rest of society, or we can be so egocentric that we can't be bothered.
I choose the actor. I observe NT's. I listen to their socializing. I practice it, so in social situations I can just emulate/mimic what is expected.
It isn't natural for me, but it enables me to "fit in".
It is VERY tiring and draining, but at least we can appear like them even though it is an act. Like being on the stage.
They can't see it is emulation, and so we are accepted.