Before the Suicide Mission
There are things left undone, a couple of squad members whose concerns she still hasn't seen to, shields that could use an upgrade, but she's out of time. The Collectors have her people and she's going to get them back. Miranda accused Melanie of making the decision to go through the Omega 4 Relay now emotionally, but she's survived too many life or death situations to leap into this one without thinking. Sure there are risks, but she has to weigh them against not just the lives of the crew members that were taken, but also the colonists that will continue to be abducted if she waits.
She's told Joker to set course for the relay and as she sits alone in her cabin, Shepard remembers what the Illusive Man told her, that her team and their focus had to be strong if they were going to survive. For the most part, her squad seems ready, but what about their leader? Does she have unfinished business? She doesn't have enemies that haunt her like Garrus or Samara; they only adversaries that really matter to her are the Reapers. Nor does she have family problems like Miranda or Jacob; she'd have to have a family first.
Personal troubles like Kasumi's though; that's a more complicated subject. Certainly, she'd made a mess of things with Samara. She hadn't been sure what kind of relationship either of them was looking for, but she'd been certain there was a mutual attraction, and since facing down Morinth, Melanie had felt more comfortable exploring it further. In the end though, she'd pushed too hard and ended up feeling like an asshole. If she'd thought Samara wasn't interested, she would have backed off sooner, but the justicar had admitted that attraction wasn't the problem.
Melanie had admired Samara's self-discipline but she'd underestimated just how deeply it ran. Centuries of denial had become too ingrained a habit for her to move past. Shepard sympathized; the tragedies that the asari had endured would have broken a weaker person and there are bound to be scars. At the same time, she seems like a cautionary tale, especially given how much Melanie can identify with her emotional reserve. She doesn't want to end up like that, unable to be close to anyone, living as nothing but an extension of her duty.
Since her disappointment with Samara, Shepard had found her thoughts turning more often towards Liara. After their fight on Illium, she'd tried to put the beautiful scientist behind her, but she'd never been totally successful, especially recently. Her reasons for turning her down two years ago made sense to her at the time, but since then, she'd been second-guessing herself, something she seldom did. As a Specter, she rarely brooded on the choices that she made, but when it came to personal matters, it wasn't as easy. Her regret was aggravated by the fact that now, it seemed too late to reconsider. It was clear Doctor T'Soni had moved on, and she should too, but something about Liara keeps pulling her thoughts back, even when logic tells her to let go.
In spite of that, she's not worried about her focus once they jump through the relay. One thing that always distinguished her military career was her ability to separate herself from whatever problems there were in her life and simply focus on the mission she was carrying out, at least while she was in combat. It's like there's only her, her weapon, and the next target. And she has her target. The Collectors took thousands of colonists, took her people, hell, they even killed her once and now, it's time to end it. Afterwards, perhaps, there'll be time for other things; time to bring Liara the Cerberus intel on the Shadow Broker, time to try to sort out her feelings. Now, she has a job to do and no room for regrets.