It can also be useful to look at Venus. Venus is a person’s desires and a at least from a western point this is still associated with love. Venus conjunct your North Node can depict that personally defining love is an experience to you in this life. What you will come to define love may have a Jupiter quality (because of Venus and North Node in Sagittarius). Maybe you will learn (Jupiter) more about love (Venus). There is an emphasis on it in this life, which is why you can feel some dissatisfaction.
Venus is conjunct the North Node is also Venus opposite the South Node. The opposition can show up as hopelessness or a lack of balance, or lack of competence. There can be separation in love, wanting something more. I would like to enter the possibility that maybe you will discover love (Venus) in some other light such as creativity, because able to create and for it to be adore by others. The experience of Venus-Jupiter may not show up as a literal romantic partner, but a new discovered art form, a romantic, but platonic friendship, and it is possible that it may feel fulfilling. This depends on how you come to define love, in my opinion that is based on free will and experience. What I have listed are simply possibilities like most things in Astrology. It can be a lesson in this lifetime to contemplate love. Your outlook (belief) (Jupiter) will have a lot to do with what you attract (Venus) or what you won’t.
Your Pluto Polarity Point would fall into Taurus, which is Venus ruled. While the Nodes describes your nature of longing for love the Pluto Polarity Point would suggest more about where you soul is headed. Since, the point falls in Taurus (Venus ruled) and in the 9th house (there’s that Jupiter quality again) the need to contemplate love is again reinforced. Taurus is an earth sign so that can be the nod to a practical or concrete form of Venus, for example being someone you really like. You mentioned having a higher ideal about the partner in the beginning of the relationship, but then it lacks something more over time. Finding someone you really like and starting a romance, but there is no blossoming or expansion because you don't love them (belief) or learn to (3rd/9th axis) could also happen in this case.
9th house is our philosophy, belief system and often things we think about a lot because of the meaning and spiritual connection they offer. 9th house is also travel or foreign territory. Perhaps, it is physically in another place or country than you are (sometimes Taurus in the 9th house can show discomfort with travel).
Venus aspects to the Sun, Mercury, and Chiron needs to be considered too and Venus in the 3rd house, it will probably be easier for you to find clarity on those and put everything together. There may be more concrete and then would move into the themes of the Venus conjunct North Node and polarity point I mentioned above.
