Broken trust could be very difficult to mend if left unattended for too long. If you are doing anything important without her knowledge, not expressing your love the way she likes to receive love, then she could be suspicious of your intentions. Its important to have trust and transparency in close relationships. Try to be as transparent as possible, where ever needed.

Needs psychiatic assessment.and if she is suspecting you and also lit bit suspicious in general indicates that she is under psychological trauma usually we call delusional thinking.and she can be helped with antipsychotic medication