Yo so, I may be able to help a little bit.
These anons are on to something, but you don't have to send yourself into galactic orbit to take to heart what they are saying.
Right now you are still young, but you're not as young as maybe some of your friends, and most likely not as young as the people you are trying to establish this feeling of "Fuck yeah, this is what I want" with.
Am I wrong? Do you primarily get with younger women, or at at least in the age range of 18-25?
You have a manifestation of what perfection is in your head, and this manifestation has (sexually) become visualized into a perfectly pleasing aesthetic.
"I want to be with someone perfect, and this is what my brain thinks perfect is, so I want to be with this."
You're obviously not fucking stupid, because you're asking the super important question: "How do I change the way that I think and perceive the things outside of me?"
You want to do this because you don't like how you feel, and how you feel is a result of your desires to find perfection in your partner. Right now that perfection is presented in your brain as physical perfection, but what do you suppose the chances are that you're actually queuing in on the fact that these people you are seeing also have no fucking clue what is going on in life, are still figuring their shit out, are probably just as likely to be dealing with their own warped expectations of reality, AND fucked up in the head as you are over the whole thing?
Take a breath, chill for a moment, and wonder if you trust your brain/spirit/ego/subconscious to give you everything straight out.
Our minds are renowned for approaching our conscious self with riddles, images, and irrational feelings and associations; do you really think that the look of someone's meatsuit, especially when ONCE found to be good enough, is going to turn you away?
Nah dude, I think maybe your brain is trying to tell you something else.