I know how you feel, because I do the same thing. and its fear of rejection, not setting boundaries and feeling like you cant say no to an invitation. I mean, setting boundaries up front will chase some people away, and it seems that when I first meet someone I feel vulnerable and when we find ourselves feeling vulnerable we sometimes make accommodations, or offer more of ourselves than we can deliver (think of when you meet someone and they have some boy scout thing for their kid, and you volunteer for something next week, and then you are like "why the heck did I say I'd go and hike with these people?!?!"). But I think boundaries can be negotiated afterwards, I mean it'd be hard to negotiate all the boundaries of a relationship of any type up front, except those that are like, work or professional relationships. because friendships and relationships grow and progress and change. Just because there is some tension doesn't mean that that person doesn't want to be your friend or wont invite you to a Christmas party ever again. now, I have to remind myself that if you KEEP saying no, if you always turn down invitations or cancel last minute, yes people will stop inviting you. But if its something that turned up last minute, well you can explain that. And if setting a boundary (like, my kid comes first, or whatever) causes tension and resnentment, that might be a sort of revealing moment: is this person so self involved that they cant realize that they aren't the central figure in my life? if so, then ditch them. If you feel tensions, but that person comes around, well then just chalk the tension up to miscommunication. The tension you feel can sometimes just be the person processing their own negative issues, or the frustration of rearranging their short term plans in their head, its probably not directed at you. Just my two cents.