Note: I had to rely on Google for translation.
Fantastic observation It still amazes me how much people allow expectations and fantasies override basic observations in people. I know what I have learned on my life path is in relationships there are three unique factors or knobs that we deal with. Physical attraction, relationship compatibility, sexuality compatibility. Take that with a persons gender spirtuality where is one side of the dial (like 9 o'clock) and masculinity is 3'oclock and asexual is noon or 6 and if the sexuality is positive or negative you get the drift. Sexuality preferences follow the same rule except noon is "bisexual" and 6 is asexual ....
So we sit with our preset notions and desires to match up with someone and build our "expectations" you talk about. The big question is when does one realize the most important thing is how we communicate and actively listen to our desired partner and opposite half are trying to connect with.
What I have learned in my travels is parts of me is very masculine (loyalty, protection, desire to serve), and yet parts of me is very feminine (joy in being taken and consumed, love of communication and community). So for me to look forward I have innate bias and desire to find in my partner and people that communicating with me my missing "puzzle" pieces to my soul / being.
Now take your commentary on expectations and living in the moment and not trying to force ones bias and expectations on there other and overlay above what I suggest. At that point, I believe it proves that the purest joy is in letting a person breath, be themselves, and actively listen and want to help their partner where they are weakest, and in turn you do the same. At that point 1 + 1 = 3 and pure joy comes forth.
Thank you (and hopefully google translates this if it converts it back) for a wonderful read.