Trust is a MUST in a relationship. It does not matter whether you are talking about being faithful, financial matters or simply sticking to promises. If you cannot trust your partner your relationship will never work long-term.
There are lots of reasons why you cannot trust someone. They have been unfaithful or untrustworthy in the past, maybe they did not tell you the truth about some minor things and you find yourself asking what else they weren’t entirely honest about.
Maybe they have been acting out of character and being unusually secretive about things. OR it could be your gut feeling telling you something just is not right!
Do not let the situation fester and continue speak with them and if you do not get a sensible, honest answer. Get out while you can, end the relationship.
Allow yourself time to heal, move on, learn from this, and look for the loving relationship you deserve.