I think the alternative to not putting up boundaries is that you just end up feeling hurt again.
In my life I've noticed that in many groups of friends or in families, there are assigned roles. I'm not sure how it happens, it just does. Some people are expected to be 'in charge' and be the takers, and others are assigned the role of follower and giver.
I've been a follower and a giver in the past, but in the last couple of years a combination of ill health and just growing up and maturing has forced me to transition away from that 'follower and giver' role.
The 'in charge takers' have reacted very badly to this, even though I'm behaving exactly as they have behaved, they still want me to be the old compliant me. As a result, I've been shunned. Literally shunned in some cases.
It's been heartbreaking and it's a side of life I could happily have lived in ignorance of. I am in a position where I now have nobody in my life I can rely on. Not a single person.
While it hurts, I also feel really free in an odd way because now I know exactly where I stand and I'm not going to waste any time putting effort in to those old relationships that never meant anything to anyone but me.
I hope you can still find good people in your life OP.