You need a cause and cannot remain in one
Two things hold at once. You need to belong to something that means something, and you have never managed to stay in one past the point where it becomes an institution. Pluto in Sagittarius in the 11th house puts the search for meaning into community.
The Sagittarius half is not personal to you: it belongs to a birth cohort covering many years, since Pluto colours the whole span alike. The 11th house is what your birth time added, and it is the individual half. It aims the searching at your circle and your hopes for the future, which is why the significant collectives in your life were causes rather than social groups.
What set this up
Somebody early on belonged to something totally, or refused to belong to anything, and either way the model you absorbed was that membership is a serious matter with consequences. It arrived without explanation. That is why you cannot join anything casually and why a group you do join gets far more from you than it asked for.
You leave when it becomes an organisation
You commit to a collective completely while it is still about the idea, and you leave the moment it starts being about the organisation. Every one of them makes that transition. Decide in advance what you will do when it happens, since your instinct will present departure as integrity and it is at least half boredom.
How the departures read
To the people who stayed you abandoned something they were still building, and to you the thing had already changed into something else. Both accounts are honest. Say what has shifted for you at the halfway point, since a stated disagreement gives the group a chance and a sudden absence gives it a verdict.
What a movement needs from you
You are excellent at the founding argument and poor at the decade afterwards, and every cause needs both. That is not a failing provided you are honest about which part you are supplying. Say at the outset which one you are there for, since everybody has been assuming the other and planning accordingly.
Your friends are from the causes
The people closest to you were met through something you were both committed to rather than through proximity or circumstance, and the friendships have generally survived the cause itself. That is a good filter and it means you have almost no relationships that were not forged in something. Keep one that has no purpose in it at all, since not everything has to be earned.
A picture of how things ought to be
You carry a specific and long-standing sense of how people could arrange themselves better, and it drives considerably more of your decisions than you would admit to anybody. It has almost never been stated in plain words. Put it into three lines this year, since an articulated aim can be worked towards and an unarticulated one only produces enthusiasms.
You gave to the cause before yourself
Money and time have gone into collective ventures at points when your own position could not really support it, and the giving was genuine rather than performed. It has also left you exposed more than once. Set the annual figure in advance, since a limit decided in a calm month is the only one that survives contact with something you believe in.
A partner has to share the direction
What you need is somebody pointed the same way, and shared values matter more to you than temperament, history or anything conventionally romantic. That is a real criterion and it should be tested early rather than assumed. Ask the direct question in the first months, since discovering the answer at year three has happened to you before.
They watched you join and said nothing
When you committed to a group, a belief or a movement, your relatives had opinions they mostly kept to themselves, and the unspoken disapproval has been sitting there for years doing quiet work on both sides. Ask what they were actually worried about, since it is very unlikely to be the thing you have been defending yourself against.