I need help with my girlfriend?

i need help tryin to figure somthin out with my girlfriend shes always turnnin her phone off when im around her or she wont let me see it but she looks at my phone all the time and when i do see it with out her knowin she has random guys textin her callin her hun and sayin i love u and stuff and when i talk to her about it she just says they have the wrong number or they sent it by mistake what should i do or say to her