Is it right that my gf can only send me a text with one x ?

but she sends texts to other guys with 2 or maybe possibly more ? everytime i ask her about it she says does t matter its only a x i no its only a x but surely cause im her bf i deserve more than these other guys ? also we have like these weird patches like one week well be all happy and close and doing sexual things ( hugging kissing ect) then the next week shell hate me never wanna see me always be horrible and just basically say harsh things ? ........ i duno what tto think of her nomore if shes mentally ill or if shes just not with it ?