Or is this something that is not acceptable for me to say as it is not really a boundary but trying to control?
IMO what you are saying is entirely acceptable, and wise. It's been my experience that people who tell me I need to trust them are people who are trying to get something from me that they want. Funny how no one has ever said this to me except for drunks and drug addicts who have lied to and cheated on me. I also have been in your situation where they say I need to trust them but do nothing differently to show they are trustworthy.