Yes that's kind of my point, that the game isn't about the BF or his importance to her/the story and isn't meant to be. As I said, he's a Macguffin and plot device. Everyone knows and accepts that but my point is if you kept the same character but made him competent at sex but otherwise the same bumbling incompetent idiot who isn't actually a part of any real ending, it wouldn't impact anything else but it could add some needed tension to the cheating since at least he has SOMETHING going for him as opposed to nothing going for him and is a dud in literally every aspect of his life. I just find the bf in a coma and cheating on him to be weak and flimsy. Is it really any different then any other scene that doesn't involve him at that point? There's literally 0 risk of being caught or exposed or the thrill and danger that cheating is supposed to be about.
I'd actually say it's the opposite and that the bf has grown up and she hasn't. He seems to actually show some emotional maturity once in a while. Responsibility, guilt, consequences etc. Even though he's not the smartest or strongest or shrewdest person. Let's be honest he's a total loser lol but at least those things enter his mind at some point. While in contrast she basically struggles to giving in to her every whim and just indulges and satisfies her baser instincts without regard for consequences etc. The way she's acted in so many of the situations doesn't show maturity but the opposite. Making decisions based on the wrong reasons and not thinking twice about the consequences etc. He's wanted a more normal stable life while she wants the thrills and danger and excitement.
Anyways, again, I'm not saying the game should be some vanilla game or she should be with the bf and live happily ever after or any crap like that. I'm just saying the bf is a plot device and nothing more and can easily be replaced with someone who isn't a total failure and then at least maybe her not breaking up with him wouldn't be such a stretch of the imagination.
Her giving in to her desires has nothing to do with immaturity. She has a physiological condition, which makes her incredibly horny all the time. It's like being high on drugs constantly, which means she's always open to temptation, and it requires a huge effort on her part to resist. When people are in that state, it's very very difficult to consider consequences. But unlike people who use drugs, Anna hasn't chosen to be like that, it's the consequence of an accident totally beyond her control. So I think comparing her and Andrew on that basis, is meaningless.
As far as Andrew is concerned, I don't think he's responsible at all. He relies on her to go out and make money, and makes excuses about why he can't get a job. I mean when you're in their position you take any work you can get. And not just wait around hoping to get the perfect job. Even the job he does get, it was Anna who got it for him. If it was up to Andrew, no doubt he'd still be unemployed.
Anna is doing multiple jobs to make a life for them, and then she has to come home and do all the housework, while Andrew sits around watching TV. Never once does he offer to help her. Even Ashley helps her in the kitchen, and he doesn't even live there. If Andrew was responsible as you claim, he'd be trying to support her as much as possible.
And then when they move into their new apartment and Anna is desperate for a romantic night together. Andrew decides it's perfectly fine to go off and hang out with Ashley for a couple of hours in the middle of the dinner. Once again selfishly putting his own desires above their relationship. After that Anna gets drunk, and that's what leads to her finally giving in to her lust and having sex with Alfred ( the first time she truly cheats on Andrew). Andrew's irresponsibility could thus be said to be the main spur for Anna becoming a slut. Perhaps if Andrew had stayed home, maybe she never would have had sex with Alfred, and never would have had sex with Ashley, Carl and Sergey later that week? And maybe then, she never would have realised that Andrew wasn't the best in the bedroom?