What a tinder box! Let's look at these two personalities. So we have a man with sun in sagittarius, and it is conjunct mars and Saturn, two planets with opposite types of energy. In a mutable sign, restless, fun loving, flirty and adventurous, active with mars, but disciplined and muted by Saturn. So we start with an internal conflict in the personality. His moon in stable, earthy taurus is exactly conjunct Pluto. So we see a constant soul searching, digging for values, examining his emotions, turbulent and fierce and powerful in a fixed sign. His mercury is in scorpio conjunct Uranus reinforcing the restlessness, the quick thinking, the mood changes, the turbulent energy. With these inner conflicts going on, we ask ourselves how he will relate to another person in a close day to day relationship? He is up and down and all over the place, needs freedom, needs security. This energy is all funnelling through a scorpio ascendent, so the world sees an almost overpowering energy, turbulent, tormented. The descendent in taurus is ruled by venus, his affections. So where is Venus? In freedom loving sagittarius. It is also exactly conjunct Juno, the asteroid that symbolises marriage. And, it is not aspecting anything else in the chart. So he is looking for a loving person in his marriage, but the relationship will have to be an open easy flowing one, and in a compartment all by itself as far as he is concerned, not relating to the rest of his life. Looking for a feminine, open minded, flirty, fiery and adventurous woman.
Now let's look at the female.
Starting with Venus, because this is what he is looking for, she is in Leo, fiery and egotistical, sociable, generous, looks to enjoy life, affectionate. And she is opposite Jupiter, ruler of sagittarius, so ties in with the theme of his partner. And their two Venuses are in perfect trine. They have similar values and tastes, and express their affection in similar ways, they feel comfortable with each other on this level. Also, his descendent ruler venus trines her Venus creating a strong tie between them.
Her ascendent is a soft and easy going pisces, very feminine. It is ruled by Neptune and Jupiter. Her sun (the male figures in her life) is also widely square Neptune, bringing in shades of weakness and deception in her partner. And by coincidence, his sun is opposite his Neptune, fulfilling this requirement.
Her descendent is virgo, ruled by mercury, and mutable but picky, criticising and analysing. And on her descendent is her sun and her mercury, reinforcing the down to earth, orderly, get it clean, get it right impulse. This is they type of partner she is looking for.
Does this match with the picture we have of him? Not a lot. He has no time for details. He will drive her up the wall, and vice versa. In fact, his mars, his way of acting, is exactly square her way of thinking and communicating. It also draws in his sun and Saturn. So we have a big conflict here.
Her mars is in that solid, sexy scorpio, on his mercury and Uranus. She stimulates his ideas, and the mars/uranus is a strong attraction but it also results in fireworks. Too much energy going on. Once the sex is over, the frustration starts.
Their moons are almost exact, which makes for a similar emotional approach, they can understand each other well. But they both have to contend with his obsessional Pluto right there. This is an extremely strong magnetic attraction. However, Pluto will also want to control the moon, and transform her.
And this emotional turbulent drama takes place opposite his Uranus, demanding freedom and independence, while inflicting unquestioning obedience. Is that a set up for a lifetime relationship? Don't think so, do you?
At the same time, his asteroid Juno is on her mercury, so she makes him think about marriage.
Her uranus, which is her sense of individuality and freedom, is on his sun/saturn/mars. This is another very strong attraction, it is fascinating, magnetic. But Uranus energy is in conflict with Saturn and mars types of energy, and it is unstable on the sun. So there will be friction and separations in the long run. But the tie is strong so it pulls together and pushes away.
Her Jupiter, ruling her ascendent, sextiles his Venus/Juno conjunction, fulfilling her needs and stimulating his ideal of a partner as personified in her. To further develop this theme, her Chiron conjuncts his Venus/Juno, telling us that she will be a healing factor for him in this area, and it will be painful for him.
This analysis goes on and on, there are many many other factors to consider, these two are drawn together like a magnet and iron nails. It is in a certain sense a devilish relationship that they can't live with but can't live without.
This is all shown in the composite. The moon and Pluto are conjunct, bringing forward that important theme in the synastry, and the excessive attraction that becomes volcanic is shown by the opposition to a mars/uranus conjunction. Sun/venus/North Node together mean this is a strong love relationship as well.
So, the answer to your question, is this a short lived affair or a long term relationship? It is both. It is a flare up that can make their lives volatile, but at the same time fulfils what each needs to fulfil their destiny. Whether they stay together or not depends on the point of maturity each has reached. This is a very karmic relationship. There is enough to keep them together but there is also lots to push them apart. Which will they do? Only they will know.
This is why I indicated a horary. If the question is asked "Will they remain together" or "Will they marry"?, etc, the answer can be seen in the chart of the question, done for the moment the question is "born". Otherwise, this one is too hard to call.
Hope this answers your question.