She stayed, even though you crossed a line. Even though you hurt her in the worst possible way. Even though she trusted you with all of her heart and you took advantage of that fact. You used her kind nature against her.
She stayed, because she loved you. Because there was a time when she believed that her love was actually enough. That it could get you two through anything.
She stayed, because she honestly believed you when you told her that the other girl meant nothing. When you told her that it would never happen again and that you would stay faithful for the rest of the relationship.
She stayed, because she placed some of the blame on herself. She thought that she did something to push you away. That she didn’t have sex with you enough. That she didn’t text you enough. That she wasn’t a good enough girlfriend.
She stayed, because she believed in second chances. She didn’t want to throw away her entire relationship because of one mistake. She didn’t want to make any rash decisions that she would end up regretting in a week.
She stayed, because she didn’t want to feel like a failure. She didn’t want to give up a love that she worked so hard to find. She didn’t want to change her relationship status and be forced to explain to all of her friends why she’s suddenly single.
She stayed, because you two have history. Because it’s hard to walk away from someone who knows you better than you know yourself. Because it sucks to admit you spent so much time on the wrong person.
She stayed, because she has a big heart. Because she saw your tears, listened to your apologies, and decided that she would be the bigger person. That she would deal with what happened and move past it for both of your sakes.
She stayed, because she thought she could fix everything wrong with the relationship. She thought she had the tools to make it all better. She thought that things could go back to the way they were before.
She stayed, because she had nowhere else to go. The thought of leaving you terrified her, because she couldn’t imagine life without you. She couldn’t imagine dating anyone else, because you promised her you would be around forever. You promised her that it would always be you two against the world.
She stayed, because she had no idea that she could do better. That she deserved more. That healthy relationships don’t involve lying and cheating and sneaking around behind each other’s backs.
She stayed, because it felt like the right thing to do at the time. Because she listened to her heart over her head. Because she didn’t realize she was better off without you.
She stayed, but eventually, she’s going to leave. Eventually she’s going to get tired of hearing your phone beep at odd times and waiting for you to come home even though work ended hours ago.
Eventually, she’s going to realize she deserves better than a split heart. She deserves someone who believes that she, alone, is enough. Someone who loves her and only her. 
