When it comes to relationship expectations,

it is better to set them as high as possible, so that partners have something to live up to$.$

it is better to set them as low as possible, so that the reality of the relationship will nearly always exceed partners' expectations.

it is better not to have relationship expectations.

it is better to set them high when it comes to aspects of the relationship that partners can control, and low when it comes to aspects of the relationship that partners cannot control.