Women answer this, Girls who cheated on boyfriends too?

I dont know..i noticed shes gotta secret life or something now...always gone, dressin up before she goes anywhere, (she never cared AT ALL BEFORE) buyin new clothes an thongs, puttin all this makeup on an be doin her hair all the time before school, stayin longer at school, wearin tighter more revealin clothes, always textin up on her phone, always goin to her moms house usin the phone..?, makin sure she constantly got minutes up on her phone an says it so she can " text her brother ", last night even she supposedly went to her moms house real quick for dinner an "fell asleep" an when i called 6 hours later she didnt answer, an i called like a hour later after that an she answered all wide awake soundin an said she was at walmart an she fell asleep earlier so she didnt answer, an she thought i was sleepin so she didnt call back...then i asked what she was there for an she said to buy a comforter for the bed an shell talk to me when she gets home....2 hours later she come home empty handed sayin we'll both go together instead cuz she thought i wouldnt like what she picked out...? an then she said 'well go to the closer walmart tho instead' an i said what do u mean what walmart was u at an she named off a walmart further away then she needed to be at and i said why'd u go alone an she said cuz i was bored and i thought theyd have a bigger selection, i woulda brought u but i thought u were sleeping...even tho she didnt even attempt to call back in that short time she was 'sleepin' to being 'fully awake at walmart' ... on top of it we end up goin in her car and i get in and notice its all clean, she always has it messy and dont care about it either, and said she cleaned her car out at her moms after she ate, before she fell asleep, and she fixed her cd player in her car too somehow, which i dont understand cuz she dont understand all that wiring, thats why it didnt work for a year... to top that off she broke up with me an told me she couldnt ever be with me again (two weeks ago after a argument) but we got back together but then she told me out the blue that she donno if she could marry me tho well see she jus has this big ball of tension in her chest cuz of all the arguments i caused and times i b****ed at her an degraded her...then i find out that she made a new email address an didnt tell me about it for some reason...an she always tells me about new stuff she does on the computer, an then she tried to hide it from me so i wouldnt even know so much as what the email address is let alone the pword, and we always know eachothers pwords. we are usually real close. she was fine up until she started school in january...do u think she is has another man or is interested in some other guy but feels guilty and wont tell me? before this she was madly in love with me. i dont get why she tried breaking up with me like that and now were together again and she said that, plus all that happend above. what do you guys think?