Talk is cheap. We have all been in a situation where someone says something that we attach value and expectations to and get hurt. This happens daily and it sucks to be on the other end of a broken promise. But you need to understand that NOT everyone thinks like you do and this at times is hard to accept.
For me, I like like "no one is watching" because at my core, I know who I am. I work on myself daily to ensure that I keep being the best version of me that I can be! And guess what, I don't do this for anyone but ME, and YOU should do the same thing because YOU are also worth it!.
My outlook on "trust" is that everyone has my trust until they prove they shouldn't. Don't get me wrong, there are definitely cases where I won't trust a person right away for whatever reason and sometimes it's as simple as a gut feeling.
Your gut feeling is your instinct or sub conscious usually telling you something you might not clearly consciously see. TRUST that as well because it's usually not wrong!
I'm a "glass is half full" kind of guy so I would ALWAYS suggest that being positive, ATTRACTS positive because you manifest what you want to happen: