@kronix
From my understanding, men over yonder, in the land of the rising sun, tend to have a shit ton of responsibilities thrust upon them. And, as it happens, romance falls to the wayside. So, since they are constantly unable to truly interact with the opposite sex properly, or get rejected too often as the girls are more inclined to want a guy with greater potential or want to be bread winners themselves, the men gravitate towards idols and 2D girls such as this one. These girls are more openly flirtatious and very straight forward.
They also are typically larger chested as that is the general basic desire. They are filled with men's hopes and dreams, after all.
The "cucking", as you call it, is usually their inability to handle such situations, as they don't usually happen. And, to add, tend to be more involved with the above issue.