She loves to cook. Especially if she has to cook for Mark. No matter what she makes, he always says it's perfect. It can be a simple toast and he still finds it delicious. If she stands in the kitchen for hours and makes everything dirty, he doesn't complain. He rather steps behind her and wraps his arms around her waist. He kisses her cheek softly, so she can feel his stubbles at her ear. He then strokes a strand from her face and turns her slowly around, looking at her with this handsome smile on his lips. Sometimes it's her who kisses him, sometimes it's him. But after their tender kiss he always asks if he could help his 'lovely and amazing girlfriend', although he only can cook about ten different meals.
It's during cooking that she realizes she loves him.

She sits on the couch, her legs close to her body and her fingers are scrapping the label from a water bottle. She tries to look all normal, she tries to pretend nothing happend. She tries to pretend that her dad is alright, that he's not a drunk who called her a bitch some minutes ago. She tries to pretend that it's not hurting her. A stupid movie is on Tv and she watches it, just to seem normal. But as Mark comes back after some minutes, he sits next to her, his hands hidden behind his back. As she looks at him questioning, he hands her some Reese's and a Disney movie. Because he knows how much she loves movies like this when she's sad.
And that is when she realizes that he will do anything to make her smile.

She's in Boston, because the Chief decided to send her over to Mass. Gen. for some days. It's her first day over there, and she misses Mark badly. She just wants to hear his voice, so she calls him. Although it's about 2am. He told her he would always be there, he would always answers her calls. But he doesn't pick up. Lexie tries it three times, then she gives up on it. While she puts her head back onto the pillow, her hands kneets nervously.
She realizes - deep down - that she is terrified of him spending the night with someone else.

She can't sleep the whole night. Because Mark still didn't call her back, and the though of him cheating on her grows worse and worse. It's maybe ridiculous, and probably not true at all. But she still fears it, because she doesn't know what she did to deserve such a great man like him. It's about 5am -she still didn't sleep a wink- as she hears her phone vibrating. It's him. He explains that he was in surgery and as he came home, it was about 4am. He didn't want to call back because he didn't want to wake her up. But without hearing her voice, he can't talk to each other on the phone for minutes, then both fall asleep, still with the phones in their hands.
She realizes that neither can sleep without the other.

It's her birthday. She turns twenty-five. He planned a little celebration for her at the hospital, with all her friends. The night, he takes her out to dinner. Just the two of them. But then he grows distant over the next days.
She realizes that he thinks he is too old for her.

It's his first chemotherapy. He is nervous and also afraid. Of course he would never admit it, but she can see it in his eyes. As it starts, pain is written all over his face. He tries to explain her how it feels, and it's like his body is burning. Nothing can ease his pain. No movie, no water, no food. But as she stands up and comes closer to him, as she kisses him softly and then sits down really close to him, as she takes his hand in hers and softly caresses his cheek, a sigh of relief leaves his lips and he smiles slightly.
She realizes that he might need her just as much as she needs him.

It's the day of his first surgery. Derek will operate on his brain, while Bailey will operate on his spleen. The whole time long she's nervous and anxious, but of course she doesn't show because she has to be strong for Mark. She holds his hand till they bring him into the OR. During his surgery, she doesn't move an inch. Till Mark is about to die. She can see his not present heartbeat. She can see his open brain. She can see blood everywhere. He's dead for more than three minutes, and she feels so lonely. She feels like her life has no sense anymore, she just wants to die to be with him.
It's during his death that she realizes that when she looks into the future, all she sees is him.

She just found out that she's pregnant. And to be honest, she's scared because of this. She actually didn't want to have children of her own that soon, she wanted to make a good career. She wanted Mark to be fine again before they start to plan their future together. But as she tells him, his face starts to shine. He smiles from ear to ear and closes his arms around her.
She realizes that he's the man she wants to have kids with.

It's his first day back at work. She can't say anything to make him stay at home for another week. He things that he's ready for it. She's pissed, but since she loves him she kind of respect his decision and let him go after he promised her to just perform one surgery.
As she drives with him to work, she realizes that she cares about him a lot.

She didn't hear from him the whole day. She doesn't know if she should be relieved about it, or worried. So she decides to look after him. Since he isn't in the plastic wing nor in the ER, she supposed he's performing a surgery. And she's right. As she enters the scrub room of OR2, she sees him making a rhinoplasty. She watches him for some minutes because he seems to become weaker and weaker every second. Just as she enters the OR, he collapses. Fear streams through her whole body and she quickly rushes over to him.
She realizes that she always will be worried about him.

They scream at each other. In the middle of the hospital they scream at each other. She's angry because he doesn't listen to her. She knew something like this would happen, she knew he should rest his body. He shouldn't pretend like nothing happend. Their argue is getting worse, a crowd gathers around them. They don't think about what they say anymore, and Mark yells that this was his third surgery, so of course something like this can happen.
This is the moment she realizes he lied at her.

Tears are streaming down her face. She just explains him how she felt during his death. That it was the most terrifying moment ever. That it's been three minutesin which she thought he would be dead, three minutes in which he was flatlining and bled everywhere. She explained that she never felt so lonely in her entire life, that her world broke apart. That her life had no sense anymore and that she has wished to die. But he just shrugs.
She realizes that she could lose him any second.

She makes an ultimatum. If he will go back to work, she will pack her things. If he will go back to work, she will be gone. Deep inside, she knows that she won't survive without him. But she says it anyways. And the world stops as he turns around and leaves. Her body is frozen as she watches him leaving.
She realizes that she's all alone.

She sits in Abby's apartment and sips on her non-alcoholic beer. In the corner of her eye she can see her boxes standing in the floor. She made her words true and left, without a note where she is. A single tear leaves her eye at the though of Mark. With cold and trembling hands she wipes it away.
She realizes that she already misses Mark like hell.