You ask an excellent question, Runforjoy: how can we know when it's ok to be honest about what we feel?
This will surprise none of you, but I have a little image that can help with this. This is a good exercise to do on a big piece of paper actually- or a small one- or whatever- the point is, I think it's helpful to write it out so it's concrete and easy to look at.
Think of concentric circles (you know, the kind of circles you see when you throw a penny into a lake and all those circles form from inward to outward in the water? or the kind of circles you see on a target? yep, those kind of circles).
In the most inner circle, write the names of your closest people. In the next outward circle write the names of your next closest people. And on and on outward until you feel you have enough circles to illustrate all levels of relationships you have in your life.
Now, the way it works is that those people in your inner circle are the ones who you are supposed to get to be the most honest with, the most vulnerable with, the most everything with pretty much. As a relationship moves outward on the circle chart it is less safe, and therefore appropriate, to be as honest. This doesn't mean relationships farther out on the circle chart aren't worth having; far from it. It just means that they are different kinds of relationships than inner circle ones. Whereas a pretty far outer-circle relationship might be what you have with the postman who is super nice and you talk to him every day and really like him but would consider him more of an acquaintance than a friend, an inner circle relationship is a best friend, a significant other/partner/spouse, maybe your therapist, etc.
This first chart you make is for current day. Circle charts can change over time, since we meet new people, grow apart from some relationships, get to know better someone we thought might only be an outer-circle friend/acquaintance, etc. In general, inner circle relationships are those that are long-standing, have been tested over time, and found to be strong, safe, flexible, accommodating, and able to evolve as both people involved evolve and grow throughout the years.
Doing a circle chart once in awhile is a good way to keep track of the status of our relationships, and it is a concrete way of illustrating which relationships we can tell the whole truth in and show up as our whole selves.
I hope this circle chart things makes sense. I'm way over my self-imposed curfew and may not be thinking all that clearly! You'll let me know if you have questions...