Alright, so some of you don't understand the too-proper couple we just looked in on for a few chapters. Let me be obnoxiously full-of-myself right now and annoyingly argue to you all what happen.
OK, so the problem with Glasses was that he was acting like a little wimpy "M'Lady" moron and not being assertive with her. This sorta was caused by his wife being shy during sex and not fully embracing herself as being a sexual being (being OK with being sexual); so out of respect he was being considerate but to annoying unattractive levels ("Is this OK? How about now? etc."; "I see you as a human being and my wife, Honey - not just some woman to just lust after"; "No Items, Missionary Only, Final Marital Bed."; etc.). This foundational problem was done away with when they were in the clinic waiting for the Ob/Gyn dealing with the main couple we're following. During that time, they saw how Mu-kun was openly lusting after his pregnant wife in public and wasn't making a big deal of it. Later on, they overheard the Ob/Gyn talk about how to be safely proactive and lustful in bed during the pregnancy period. Even going so far as to suggest trying anal; which is mind-bogging af for them because they're treating marriage as something that must be 100% at all times to be upmost sacred and HERE'S ANAL BEING SUGGESTED TO A PREGNANT WIFE. So after this experience, Redhead wife picked up on this and finally understood she can be a sexual being despite being a wife: it's OK for a wife to be lewd for her husband.
Unfortunately, Glasses still didn't pick up on this like Redhead did. This dude STILL kept being all "Oh no, she's my wife. I can't see her as a lewd sexual being. I must treat her with the upmost respect. Even when she's given me permission to act lustful towards her!" EVEN AFTER THE CLINICAL EXPERIENCE. He still didn't pick up on the fact that sometimes women want to be "taken": they want to be fucked by a confident assertive man, sorta beast-like. Sometimes instead of just doing missionary, go for doggy-style or an obnoxious mating-press or some freaky standing shit with the laundry machine on (take advantage of those vibrations, men). GO AIM AND HIT FOR SHIT THAT HASN'T BEEN TOUCHED RIGHT. Yet, he still kept putting her on a pedestal instead of on equal footing like a partner should be. Once he saw Mu-kun in that lustful beast-like position over his wife, it finally clicked on him. "Ah, my wife wants me to ravage her like a man. Bonus, I have a chance to defend my marriage to her too like an assertive and confident man." He finally got the idea it's OK to FUCK, not make love, sometimes and blast some "I-needed-that" loads into her.
That's my 2 cents on the situation.