I see it like this. I was codependent with my first boyfriend and spent way too much time with him. Even now I know some good friends who will just disappear after they start dating someone. There are some couples you always feel like a third wheel with and make you feel like you're bothering them. That isolates you from people and opportunities even if you don't want to be. Now I'm careful not to give that impression. It takes conscious effort to maintain your other relationships, work on yourself, and commitments.
With Laura she doesn't want others to pair her with Lukas and isolate her so that she's only known as "Lukas' childhood friend and future (likely) bride." She wants her own skills, friends, and identity. She doesn't really have to break contact completely, but it's hard to forge a new identity with the shackles of an old one of 8 years. Plus I understand the impulse.
Her entire persona and how people around her act is written like NPC dialogue around the plotline of their childhood friendship. That alone has gotta be insanely uncomfortable. If it were me I'd def want to find some way to "prove" this world is real even though it's within a game and by extension my life is valuable here by showing I can break away from what was written in the rpg. If she stayed as is with Lukas and didn't break out of her role it'd feel like there was no self-determination and knowing your fate at the end of the road.