Similarities Between Romantic Partners

When I was younger, before I was a rationalist, I was told that "opposites attract" in romantic relationships.  Did the person who told me this mean it in the sense that it is supposedly some ordinary phenomenon for people to be romantically drawn to someone who is different from them, such as when it comes to personality?  Did they mean that it is actually good to seek out a partner who is psychologically different from oneself?  I am not sure if they only meant the first sense or also the second, but this is entirely erroneous except in that many people, being non-rationalists, might asininely end up staying in romantic relationships with people who are not really compatible with them—much less rationalistic, morally upright people.

Marrying someone who is unlike you hinders intimacy or introduces great troubles, if not both.  This is a basic but vital logical fact about marriage.  One does not need to be told nonsense about how (supposedly) "opposites attract" to then realize why it is of great importance for the stability of a romantic relationship that both parties are compatible up front.  Marriage is no exception.  With the strict exceptions of things like complementary skills (not on the basis of gender, but individuality) or differing hobbies that can be conducted in a way that does not irritate the other party, someone has to be a special kind of idiot to think that intentionally or recklessly choosing a partner with different personality traits or behaviors is in any way rational, morally valid, or even pragmatically beneficial to the relationship.

You have no control over whether someone else changes their beliefs or personality inside a marriage, especially for the worse.  Just to clarify, of course it is only valid to change an irrational belief (either it is logically impossible or demonstrably untrue, or it was simply assumed to be true even if it demonstrably is) for a rational one; all else is objectively erroneous.  But, at least the starting point leading up to the beginning of the marriage can be carefully engineered to involve genuine compatibility.  Somehow, many people act like they are incapable of or absolutely averse to 1) being rational and self-aware and 2) selecting a partner who is both of these things and actually similar when it comes to personality.

Irrational people might pine after someone else even if they themselves have thought of how they and the recipient of their interest are not really compatible—if not on the level of worldview, the ultimate level of compatibility/incompatibility that non-rationalists often neglect, then on the level of personality.  Even if two people both hold the correct worldview (rationalism and various things which stem from it), do they have the same desires, goals, and habits where there is freedom of individuality without believing or doing anything irrational or immoral?  If there are differences of personality, are they simply pretending like they are not present or refusing to take them seriously because they feel so in love?  

Two people do not have to like the same television shows or even both like watching television or streaming shows, for instance, but if this leads to any lack of alignment in other ways, then even something like this is a blatant mark of incompatibility.  Waiting until marriage to intentionally discover and communicate such things is a surefire way to place the relationship on a weak foundation.  Some people might, for the sake of either assumptions or emotionalism, put little to no effort into thinking about significant philosophical issues—including compatibility in marriage—and their relevance to the context of their personal life.  If either partner sincerely expresses their authentic self in the marriage, disparities will probably rise to the surface very quickly.  Both partners could contribute to this idiotic negligence before marriage, certainly.  At least one of them has to in order for this to ever be a problem.

They are ideologically and relationally negligent in that they actively or passively wait for some personal experience to prompt them to ponder something major, when it is both often logically obvious what the truth already is from pure reason itself and when they to an extent damn perhaps the entire course of their life from not acknowledging tbe truth ahead of time.  And yes, remaining silent about such things before a marriage unless due to very specific reasons (such as having to focus on major life problems) because of assumptions, emotionalistic obliviousness, and unwillingness to risk discomfort is incredibly neglectful towards the truth and towards one's partner and relationship.  If the marriage collapses under the strain resulting from this, it is absolutely at least in large part the fault of the partner who charged ahead foolishly.