i find a lot of angles in this question. i'm going to type them out but i kind of want you to just Te tear what i say apart and simplify it for me.
the first is the question of what a relationship is SUPPOSED to be. what makes sense for relationships, how that fits into individual human beings having fulfilling lives and developing themselves and their desires in ways they see rewarding and meaningful. i struggle to understand if the idea of monogamy is ultimately one of those like taboo ideas that you just have to accept at face value to participate in the "serious relationship" game. and the way in which that game intersects with sexual discourses is so muddled and messy- it's frustrating for an N who wants to assimilate all the perspectives and synthesize them into something TRUE.
sexual behavior/practices and the idea of a long-term relationship seem connected in fuzzy ways to me. what this comes down to is CHEATING, which even the language for it is so contractual and legalistic, it has to do with accepting the binding law for a life partnership, a business venture that starts out and proceeds thru a series of phases/transformations intending to build security at a reasonable socially accredited level/way. these are important, i understand, for individual persons to be able to make their way in the world, part out their work, and focus on certain tasks that they can learn and develop skill for in order to do better and w/ more specialization. ie that i won't have to make the money so i can write books, create a pleasing domestic environment, organize leisure and learning and self-improvement, etc. but the ways in which these limit relationships with other human beings can be a huge crutch for development, and this relates to sexual practices as well (which is a serious and valid language for expression, exploration, etc between two people and a way in which they know each other, encoutner each other, and dialogically define themselves thru their experiences with others, positioning themselves within gender discourses, social status discourses, anima animus shit, aesthetic development, T-F balance, clean out the pipes, etc).
i recognize all these aspects to the equation but my short answer is HELL NO. i'm way too insecure. i understand that my idea of a relationship, particularly a serious long-term life partnership relationship requires many artificial constructs/boundaries for me to have a reasonable level of confidence/trust in the situation. and i would like to point out that THIS is what many of these relationship structures do, what they are there for. it is not any inherent truth to the way in which relationships should or naturally unfold, it is just necessary precautions and like a LANGUAGE for relationships so taht we can appropriately read and respond to the situation. they are not more RIGHT in any way, but certain individuals need more explication, need stricter requirements and tighter socio-sexual boundaries to feel safe/secure/confident/trusting as a partner.
i am a 5w4 enneagram wise. my tendency is to withdraw to protect my own autonomy and not get over-extended/exposed by the weaknesses that are created in attaching to another (individual or group). i want more control over the articulation of my self, my self-image, my story/narrative of self, my idea of self, my future self projections, etc. anything that threatens these or jeopardizes my ability to do this, or forces me to swallow some bad Fe blood that is disillusioning regarding this, questions and interrogates my ways of integrating my-self as an identity and idea of who i am and who i relate/stack up to others, (which is very 4 wing- wanting to be recognized as a uniquely valuable individual who stands out and is not like the others, is never lumped in with "the rest," etc), just punishes me for idealizing something in a way that is not accurate, or makes me have to question my own Ni connections stored away and update my shit and feel LOST in liminality and unknowing and uncertainty as to who i am, what i'm doing here, and how i relate to others socially, sexually, self-preservationally (success!), etc.
i would never accept it from someone else. in terms of what a relationship brings to me, i'm realizing my unrealistic expecations to be loved in like another higher better totally categorically different kind of way is silly and absurd. human beings are built to desire, like, love, learn from, fuck other human beings. but i do know that the added security from someone who wants to take care of me (especially in terms of worldly and practical things), attend to my emotional state and wants to nurture it, care for it, etc, is a very significant for me. whereas some types are more inspirational and help release and express big waves of emotional torrent, others ground me from the storms. this ebb and flow is a difficult question to master and only LIFE can answer it, radically contextual and highly situation specific. i don't know what will happen, and it is the nature of highly advanced social beings to have many diverse and conflictin desires that must be managed and maintained. but each person kind of has an obligation to do the best tehy can for themselves, do what they need to do. there are hopefully built-in obligations (dependencies!) to others as well, but they ARE secondary aspects of a life that is ultimately your own to live.
it is difficult at times for extraverted judgers to turn your own judgment on yourself and your own actions in a way that allows you to stay in touch with your own wants and needs. whereas introverted judging types follow their hearts or their logic in an easier way.