Just out of curiousity, what aspects in synastry do you see that indicate two people being soulmates? I'm not talking about just romantic but also in family and with friendships.
I see the Nodes being significant and planets that touch the angles as well.
Personally, I think North Node and South Node and personal planets and Ascendant/Descendant conjunctions are of soulmate and karmic nature. Squares and oppositions too. (Not that much sextiles and trines - those are helpful yet it's the hard aspects that get our attentions so those are the ones I consider.)
Also, I'll mention a book (with Gemini as my dominant chart signature books are always on my mind): the late Robert Blaschke has a big and amazing section about this topic in his book on relationship astrology.
He saw Moon or Sun or personal planets conjunct the other person's IC as soulmate material. He saw the two people as being relatives in a past life.
He also said that luminaries (sun and moon) and planets conjunct the other person's South Node were this kind of soulmate connection too. He did say these weren't easy connections (I found this to be true and still couples can be together for a long time.)
He also mentioned conjunctions to the other person's Vertex.
I personally only take into account personal planets conjunctions to the angles, IC and Nodes as personal planets are more personal and tend to move quicker than the outer (neptune, pluto, uranus) and social (jupiter, saturn) planets.
A quick afterthought...I think I would definitely consider conjunctions involving Saturn and Jupiter if these planets rule the angles (e.g. Aquarius, Capricorn, Pisces and Sagittarius), especially the Ascendant and most especially the IC.
I would also consider Moon conjunct Venus synastry
It gives a lot of comfort and chemistry and is a loving aspect to have between 2 people.
I think strong moon connections are hard to beat, they really touch the heart.
Nodal contacts to planets and angles. That person feels part of your souls journey somehow. I have strong nodal contact conjunctions with each of my family members!
Neptune can sometimes give this soulmate feeling too, but gotta be careful with that one.
Would that include one's Moon falling into the other's fourth house? I have that aspect with one of my good male friends as his Moon falls into my 4th house. On that note, are the houses just as important in synastry as planetary contacts with each other and the angles?
strawb. said
Nodal contacts to planets and angles. That person feels part of your souls journey somehow. I have strong nodal contact conjunctions with each of my family members!
I only had that with my maternal grandmother. Her Aquarius Venus was conjunct my IC and north node.