How to get out of this cycle

[greatbighillofhope]

This is a repeated pattern in my relationships- friendships and work colleagues included, I need to break the cycle.
It starts out with me trying to be helpful and supportive (ie being a good friend), doing favours wherever I can but at a certain point the other person asks/demands/expects too much of me and I have to say no. At this point I am accused of being unreasonable (despite their demands of me being the only unreasonable thing) and a bad person.
I know I need to be acting to prevent this sooner but when and how? The biggest issue for me is identifying where it crosses the line from reasonable to unreasonable, I just can’t seem to spot it in time to prevent it becoming a problem.

I would stop trying to be helpful and doing favours. This isn't necessarily what a good friend is about and I suspect your friendships are based on what people can get. Rein it in and see what happens. I'm very good friends with people who I do no favours for and vice versa

That is actually a really good point. I guess I’ve always believed that my value only comes from the use I can be to people iyswim and can’t truly believe that someone might just want to be my friend because they enjoy my company. That sounds ridiculous now that I write it down and I’m actually a pretty confident sort of person and not at all shy, but I do always feel I have to be useful to such an extreme that I am a workaholic.

There in lies the problem then! I bet you are missing out on friendships with people who just want to be around you because you are spending your time running around after ungrateful people. Sometimes the more you give the more people take.

Based on your update, I suspect the reason the people you're referring to accuse of you being unreasonable etc is because they targeted you for your desire to meet everybody else's needs at the expense of your own, and sought you ought to take advantage of that. (They targeted you, you didn't "attract" them.)

Because that isn't the way regular people would behave in that scenario. Friendships are based on liking you for who you are, not what they can get from you. I don't think the issue is with your communication and assertiveness, more that you don't see yourself as being worth anything more than serving other people. (Which I can relate to.)

Wondering if you might find it helpful to explore your self esteem. There is some decent stuff here to get you started: www.cci.health.wa.gov.au/resources/infopax.cfm?Info_ID=47

Gruffalina, I think you could be right about that. I do seem to be ‘pursued’ by people who want to make friends with me and then they start wanting more and more attention. I feel comfortable with that just because I’ve got so used to it but it isn’t normal. Now if people don’t pursue me I assume they don’t want to be friends, so it becomes a vicious circle.