What is the evolutionary purpose of retrograde Venus?
Yes, they dont want you to do long term commitments when Jupiter or venus are retrograde. WHY? Its Because when they are retrograde they are as close to earth as possible, so after that they move further away. Which means, the event is not likely to continue to get better. With any long term commitment you want things to move forward, if they are not, they will feel like they are moving backwards. its not that its a bad thing, but we need room for improvement.
So does that mean that if a relationship started just before the retrograde happened, it will go through a bad patch, and then move smoothly forward depending on when the two energies come back together?
No, does not mean that at all. For it to go to a bad patch, there has to be some problems indicated there. THe fact that it will go retro before long shows that things can move forward more likely in the future.
People are always getting very concerned about any retrograde transit. Retrograde is misunderstood and popularly promoted as "troublesome". It is only troublesome if that planet is already troublesome in your chart. Otherwise, it is just a more potent influence, or as Ernst said, more "confident".
Very true, when a planet is retro, that planet has more effect, its closer to earth, it can do MORE now. IF you have been shirking that planet, then yes, there will be problems getting things to work. its like you have not driven your car in five years and now you gotta go on a trip across the country. You will have car problems. I LOVE mercury retro times myself and find them amongst the most beneficial times of my life. Every time it happens i discover something about the occult, my mercury is in the 8th house of the occult.