Dont know what to do about my girlfriend...?

Ok i have been with mygirlfriend for almost 3yrs. for 2yrs we been going thu somethings..but were trying to work it out...i just fand out that she had a date over the weekend i not know if she went or not..this is not the frist time i fand out she made a dat.I know the frist time this happend she didnt go...i dont know what to do.I love her we live to gether her 3 yr old calls me daddy