I don’t know why I’m fighting so hard for her

I’m been in this relationship with this girl for a little over a year now and it been nothing but a battle it’s like every couple of weeks it’s something new I’m not doing right or every time we get into a disagreement she throws in the idk how much longer I can do this quite honest the next time she tells me that I’ll be perfectly fine to walk away i have suspicions of her running through my phone which I have nothing to hide but she won’t admit to it always accusing me of doing something im just about fed up it’s not worth the head ache anymore I was holding on hoping to get 1/2 of what I invested in this relationship back but I’m just gonna have to take this L and take it as a learning experience . If you have a S/O do right by them because you don’t know what you have till there gone