Safeguarding not letting me live with my boyfriend

Yes.
If you are not yet an adult, in some circumstances adults can make some decisions for you, based on their judgment as to your best interests. You do not have full legal autonomy until you are eighteen years old.
You could seek directions from a court. You would have to have what is known as a "Litigation Friend" to represent you. A Court would take a lot of persuading to disagree with a decision made by professionals who have safeguarding responsibilities.

I’m almost 28

Are safeguarding allowed to do this?

It would depend on the whole circumstances of the matter. OK so we know you are 28. I do know that the "Court of Protection" in London has "control" of a lot of Adults. They take over their whole life basically, control their bank accounts everything. If you please give us a little background, if you can without breaching your comfort zone then please do so then can opine better.
(Just as an aside from your matter. I know/knew a youngish man who happened to be a multi millionaire. He was very eccentric type ,but still very nice guy. He went to a foreign country and for some reason appeared (and im not sure whether he did or not actually) go "off his head with drugs possibly ?). Anyway somehow ot other I dont know how someone put him under Court of Protection and a firm of solicitors in London were placed in charge of his bank account etc. He was still in foreign Country . He started posting on Internet saying he had no money etc etc to live eat
as solicitors were not giving him enough. Bear in mind this guy is multi millionaire from his own hard/clever work and still mid twenties. Anyway he finally came back to uk, they detained him , put him in "a place" for his safety (thats what they say). He got his lawyers involved and end story is the Court said he was Eccentric NOT Mentally Ill.