Steve, theoretically it's like you say, but in practice things often change.
You have been burnt by a recent friendship and apparently are not able to get over it yet.
I have been burnt by a friend who, although I gave him full trust, started to take advantage of me. This relates to $$$.
We can write or speak as much as we want. That friendship has ceased to exist to me. I feel betrayed. Also, this episode has undermined the word trust to me. In future and in next lives I'll be much less trusty in business (reads: no trust at all).
You may be rite mccoy. Trust is sometimes given too freely and perhaps we are somewhat naive in the trust we give to those around us. What interests me more is the square you have in your chart from the Sun to Neptune. The house of resources held with others and friendship. i have a similar square in my chart. It often blinds one to the true purpose or intentions of friends. It is a karmic factor working out from previous lifes. The chart always shows us factors we are encountering from previous life episodes. The question to me is how to handle them. This is a spiritual question. We often hope that by placing are writing strategically or by speaking to others that they will grasp what they have done. Even if they can't or will not... at least we tried. Then of course we have our own lessons to learn from such encounters also and to be careful we do not over react and begin a new round of karma for ourselves.