[slaggard]

if it walks like a duck, squeaks like a duck,,,,,,what is it ?
its a duck,,,,,daaaaah !!

my personal thought is this, there is no relevant explanation as to why she has to save a different name with your no. this is what we call coding. i did it before i got into a committed relationship. its a way to deal with incoming calls from your other lover/s incase they call. to be honest, there is no other reason for her actions besides cheating.
i suggest you do several things cuz u will need to do damage control. DONT CONFRONT HER. deny her access to your atm cards, and all other personal information. without raising alarm withdraw all those privilages.

play her game on stealth mode.

get another galfie on the side preferably her best friend or close. very soon her true intentions will be revealed. what u need is a distraction to avert the emotional hangover.

this are the deductions;
1] the name change is to convince the other lover that the numerous calls you make are from a galfriend.
2] she must be spending alot of time with that other guy to consider you a distraction.
3] she must be meeting that other guy in a private setting eg apt/house. sorroundings that invoke the fear after laying down the cell.
4] i believe the other guy has no clue she has a boyfie. he is been played just like you are.
5] she is a cunning biaaach

her friends will cover her just as your homeboys would cover your ass if you were cheating.
its not worth living in fear or suspicion, just declare war and move on with another agenda.
the biaaach gots to go.