Well, I think how Venus in 1st opposing Jupiter plays out in our relationship is we seem to agree on how to have fun, what restaurant to eat at, taste on aesthetic things, with Jupiter opposing, we probably encourage each other to over-indulge
ha!
On a more serious level, I think it helps us to compromise and find solutions to issues, there is a desire to please and to work things out. We were friends first and I think that is a strong basis for love & respect.
I agree with Aquarius7000 that the composite is only a chart of the combined energies of the two people. I like to compare the planets aspects from the synastry to the composite. It also seems to me that if there are not any planets in the angles (1,7, 4 or 10) of a composite then it is not a very significant relationship.
As for planets missing in angles or the angular houses not being prominent in the Composite, here is a list of couples whose composites have no planets in angles or the significant conjunctions and stelliums are not in the angles:
Paul McCartney and Linda Eastman married 25+ years
Susan Sarandon and Tim Robbins -together 23 years, 5 children
Paul Newman and Joanne Woodward - married40 +years
Johnny Cash and June Carter Cash
Jay Leno and Mavis Leno - married 40 + years
Patrick Swayze and Lisa Niemi - married 30+ years
Michael Douglas and Catherine Zeta Jones
Madonna and Guy Ritchie - only 8 years but had children together
Katie Holmes and Tom Cruise - only 6 years but had a child and ..
Heidi Klum and Seal - again not long-lived marriage but had children together.
I have more I can list but the point is made.
I think these were "significant relationships." So as I have been reviewing my files I see that it's about 50/50 marriages where there is very little emphasis in the angular houses.
I have come to the firm conclusion after 40 years of studying that the Composite Chart is the best predictor of the longevity and general level of satisfaction in a relationship. BUT human beings have many things impacting on their psyches and souls and astrology does not exist in a vacuum. Example: if two people are fundamentally different in their values and level of spiritual advancement, a great composite will not insure success. If the person you are romantically involved with is emotionally troubled, is a sociopath, or an addict, these conditions will impact your relationship very negatively and these factors cannot be definitively determined by examining the composite chart although there may be clues in the natal - but these are not always definitive either.
A good exercise for students of astrology is to take the chart of someone they would not wish on anyone , say Adolph Hitler or Charles Manson, and do some random composites with these people and your friends and family members. You will get some composites that look pretty good and some that are really troubled. But surely you would not recommend that anyone have an intimate relationship with either of these two men.
So the lesson is: people need to do their homework and evaluate the character of any prospective lover/mate before they commit or even before they do the astrology.
I have found 5 characteristics that make for a really strong composite chart for romance and marriage:
1. A conjunction or stellium with the Sun or Moon that is supported by a sextile or trine to another planet
2. A happy Moon - meaning not more than one square aspect or one opposition to the Moon. Square to Jupiter is an exception.
3. Sun or Moon not in H6 or H12
4. Good aspects outweigh the negative ones and there are no t-squares. Jupiter squares and oppositions are usually benign unless Jupiter is conjunct another difficult planet like Pluto or Saturn.
5. For longevity the nodes should fall in the stellium or square it, or on the Moon or the NNode (not the SNode) is on the Asc.
I have some articles about Composites and compatibility myths at my blog at
www.thelivingsky.wordpress.com
Barb