you have raised some very worthwhile questions here. ones which require a great deal of consideration and time. and ones which cannot be answered adequately in a brief post.

gender ideologies do exist. they influence our perceptions and experiences of what it means to be male or female. and they change over time. but, is masculinity/femininity simply a social construct? i am not sure.
i think it’s a matter of nature AND nurture.
in many ways i identify with traditional notions of femininity. for me, it feels innate and i have felt that way for as long as i can remember.
in partner: i am extremely attracted to ‘masculinity’ in men, - male physique, physical strength. for me there is nothing finer or more beautiful than the male body. however, don’t need emotional strength (or void). emotional depth and sensitivity/vulnerability in men can be very nice and very masculine.
Being a woman has been so redefined today that the word "femininity" however relevant is somewhat limiting. Young women experience gender difference quite differently from women of the past. I do think there's still a nature AND nurture thing, but nurture is currently dominating. Women view their gender as a construct of their personal, social, and emotional identity. It's not predefined anymore what being a woman is supposed to be. Women are taught to see their gender difference as a personal strength not as a weakness. This means being a woman is not viewed the fragile object requiring protection and support because of her "softness". She is no longer defined entirely by her sexual difference. Rather, her sexual difference is only one part of who she is. She is seen today as more than the sum of her sex organs. So, being feminine is not her singular birthright and occupation anymore. Being female is not a career, and subordinate to her complete personhood. Therefore, her main goal in life today is not to reflect "femininity."
However, I think women are often asked to diminish feminine qualities because they are seen as a weakness and a reflection of the old guard. Now, power and strength is only defined in stereotypically masculine terms: dominance, competition, assertiveness, control, and authority. "Feminine" traits such as "demure now equal = shy, naive, codependent, submissive (as in no autonomy), accommodation, or supportive = doormat, sensitivity = weak, fragile.". Both men and women are still "permitted" to show protectiveness and nurturing but only to family or close friends. They are not expected to show these qualities in large society unless they are in public positions. Women must often display stereotypical masculine traits to be seen as good at what they do. They are invisible or considered unaccomplished if they don't.
Other traditional masculine traits such as firmness, hardness, unyielding, highly competitive, significant mental and physical strength, logical and practical intelligence, focused, direct, concise, high confidence, high pain tolerance, less emotionally expressive, authoritative, are associated with high competence and proficiency and we expect everyone regardless of gender to reflect these traits to be considered the best or most intelligent or accomplished. When they don't, they are seen as weaker members whose contribution is not equal to the rest of the fighter and survivor population. More feminine qualities such as flexibility, accommodation, listening, and showing concern or affection are seen as signs of simplicity, and deficiency in other areas such as intelligence. Women who choose to serve in a nurturing or humble roles are seen as weaker, while those who lead and manage, are seen as women of real power and control. Strength can't be quiet anymore. It must be visible to the world and be shown in egocentric displays to be seen as real strength.
So, sadly, the feminine and masculine have been horribly disfigured and misunderstood, that we now buy into the supposed "inherent" differences between people, that they still indirectly supports the idea that one is deficient, and the other highly proficient. One of the examples of why strict or rigid dichotomies are problematic and dangerous.
Masculinity: characterized by initiating, protecting, strength
Femininity: characterized by responding, nurturing, beauty
In prospective partner: the above, with some healthy mix of both genders
A gendered world is natural, provided that the views of each gender are true to nature - distorted but not negated by cultural ideals.
Agree, in some cultures having more "feminine" qualities is ideal. In others, it's purely a sign weakness and inadequacy.
In terms of partners, I've always been attracted to "manly" men. I find physical attributes to be sexually arousing, and personality dispositions to be sentimentally attaching. I can spin it however I want with this evolved frontal lobe of mine and make it sound sophisticated: "A man of ambition, intelligence, strength of character, kind and sensitive" but most of what I like comes down to: "Apart from healthy genes, is my partner capable of providing, protecting and nurturing?", and that can manifest itself in so many ways.
I think the basis behind any attraction is: "Are we going to ensure one another's survival or not?" Let that survival be psychological, physical, intellectual, social, etc. whatever you need to keep you (and your potential offspring) going.