The discussion around the weakness of the MC seems to remain one of the main topics of the thread. And while I was myself as a viewer completely angry and demoralized seeing him letting all that happen, I think it is to easy just to say well, what a pathetic loser, well, I guess he is just not an alpha. Obviously he isn't, but what does that really mean in his particular case and is this a straightforward, inevitable thing? Weakness has a thousand shades. A few thoughts.
1. Is he weak in a male environment or towards his wife? At work he is no leader, an introvert but an average, normal guy. He would have dealt with the situation in a calm rational manner, would prob have been laid off. Only his wife makes it a battle of the egos, makes it personal. Being fired after a loss of accounts shouldn't normally be that. On the other hand at home, his wife takes over. His weakness generates here, in his relationship with her, even if it spills then over to his work. This weakness comes unspectacularly, she doesn't order him around, isn't rude, he isn't submissive, he just takes advice and is open about is dire situation. But it has two important consequences: she lies and acts behind his back by going to his boss. Already this makes his situation untenable from the beginning. And she insists on going with him to the dinner therefore making him fail the test (fantastic writing). Again: she doesn't make a scene here, it is a normal conversation. In order to avoid both, he should have known that his wife is capable of betraying him, and he should have authoritatively forbidden her to come with him (and because of her lie he didn't know what was at stake here!). Is this plausible in such a marriage today, in this milieu, within in the current consensus about gender relations?
2. From then on, in the bosses house, we have to acknowledge therefore, that he doesn't act alone but follows the plan of his wife, not his own impulses. Therefore he is bound. We have to be fair by recognizing that he can'T follow is natural inclination towards the boss in these conversations out of consideration towards his wife and her plan. Standing up to the boss would have meant standing up to her and her plan first, in front of the boss, to say fuck this plan. IN other words: she dominates him here, not his boss! His boss does it only indirectly, through his wife's soft power over him.
3. This leads to the main point, his main failure in not intervening now in her de facto prostitution: in order to do that he needed to be prepared on the spot to leave everything, his job and THEREFORE his wife and his family. All this is connected. This is the only option here, there is nothing in between. in order to bei "alpha" you have to be mentally able to exit and to let her know that. He was not.
4. We have to diffentiate between his weakness before the adultery and after. After he has nothing to defend anymore. if you witness brutally your wife's betrayal, what is there to fight for? of course his own integrity, but again, this would mean exit. IN this situation immediately after he is simply smashed. This is the problem with sex: it is irreversible, he can't fight for something he has irreversibly lost. This is a consequence of the events, not of him being a born Beta.
5. And then, in the following scenes with his wife, when she tries to repair something, there comes in a new element: disgust. That he doesn't "reclaim" her is not only being defeated but genuine disgust of her. I would rather see it as an element of dignity, he senses how hollow and loughable it would be to sleep with her - again following her plan, her need to cope etc. So we mustn't confuse disgust with weakness BUT the former can add to the latter by demoralization. The spiral goes on.
6. And, finally, we have to recognize the ambiguous role of reason and insight and curiosity adding to his weakness. That's how I interprete the toilet scene. He is driven by the need to understand to know her and her needs and her thoughts about his sexual performance. It is again easy to demand the archaic alpha here storming out of the stall. As I see it, his reason kicks in here and wants to observe (at first not as a cuck but gathering information). And his reason tells him as it is: he has lost the sexual comparison, the sexual battle. Reason here practically means displaying weakness: clearing the field for the winner. Being alpha would mean silencing reason, acting in what seems to be a lost cause. This is difficult for somebody conditioned to be rational and controlled all the time.
Drawing conclusions being alpha here would mean: being prepared to face ALL the consequences at any time, knowing when it is over and cultivating an other kind of marriage (her tatoos could give a hint that he was already careless or forgiving in choosing her).