The nodes are quite important in synastry, and his nodes crossing your ascendent/descendent axis are very important, it's very binding and alluring, and sometimes if backed up by other aspects it indicates a karmic relationship, but at any rate it draws you two together as a couple, also towards a marriage tie.
His node with your Neptune binds you two together in a learning experience on the spiritual level, he will feel very inspired by you, although he tends to look at the relationship through rose coloured glasses. It is the planet person that brings to the node person (in this case, him) their energy, so you will give him illusions, poetry, romance, although that could swing towards delusion and deception, depending on other aspects in the charts. This also reflects your natal Venus/neptune trine, so you really want and need a dreamy kind of love, romantic, flowery and poetic, and this Neptune/NN contact fills that need in you.
Your descendent ruler is the sun, and his mars is conjunct, stimulating you and binding with the relationship with you. There is no aspect table with the chart you posted so it isn't clear, but it looks like his Pluto opposes you sun. If in fact he has a mars/pluto opposition and your sun is in contact with it, you will indeed find him attractive, compelling and irresistible, although the down side of this would give you too much energy from him, he stimulates you sometimes to the point of irritation, and he tries to change you in ways that can become overbearing. Scorpio involved in this brings it into the bedroom as well, where you have a strong physical attraction that binds but also imposes.
We must remember that a relationship that turns into marriage lasts a long time, and the easy aspects help to soften the inevitable conflicts and contrasts that two people will have when in close rapport. All easy aspects would prove boring in the long run, and all difficult ones would be unsupportable, but some of each will keep the partners interested and committed over time.
Then sun/mars conjunction trines the Saturn/neptune and the NN. The trine is very positive here, because not only does it too reinforce the tie between you, but the sun/mars can also be quite volatile, it's a lot of energy to handle, and in a fixed sign each of you will tend to stick to your position and not give way, so trine Saturn (discipline and responsibility) and Neptune with NN will help you both handle the situation.
His mars in good aspect with your Venus, and trine Uranus gives fascination and sparkle, while Neptune adds a romantic touch.
Mercury trine between the two of you is so valuable, you will understand each other intuitively, and this goes a long way in compatibility.
His mars conjunct your IC, 4th house cusp, can bring some arguments into the domestic arena, you may argue when you are at home.
His moon on your Jupiter is so loving and caring, it's a beautiful aspect to have between you, in your first house, so you really can appreciate and encourage him, aside from making him feel comfortable with you. His moon in your first house lmeans you intuitively understand each other, it's a psychic tie, you feel bound and somehow at one with the other person. Not knowing his birth time is a big negative here because the closer this conjunction the stronger the tie.
Your moon trine his Capricorn stellium further strengthens this psychic bond.
Your Chiron squares his nodes, so this will result in your relationship being challenged by sorrowful situations, but you have so much on the positive side that you should be able to confront and overcome these as a couple.
Synastry is so rich, there are so many layers that can be examined and evaluated between two persons, and you can go on and on, but this hopefully will give you a start. Should you find out his birth time it could give us more vital information, without it there are a lot of uncertainties, like his moon position, and the links between your descendents, that would be very important.
Interesting also to see your asteroid names conjunct on your IC! Karma!
Enjoy this one, it's vey positive!