I may not know much, but I can tell you one true thing:
No one on the outside can ever really know what goes on between a couple.
They might be a married or an unmarried couple, a conventional or unconventional couple, it doesn’t matter. It only matters that they are a couple, bound together by some bond of intimacy. In any couple so bound, only those two even have a chance of understanding what happens between them. No one besides them can hope to get it at all, to understand the chemistry that brought them together, the psychological dynamic that binds them, or the reasons or the meanings for the things that they do.
You may wonder why man “A” wishes to be with woman “B,” but never for a minute expect your wonderings to amount to much. You cannot understand it. Why would woman “X” remain married to man “Y?” Don’t waste too much time thinking about it, you don’t have enough information upon which to form an opinion. That information rests with the couple, with them alone.
So if you find yourself a’wind of something that is happening to a couple that you know, do not form any conclusions about the behavior, or, if you do form opinions, don’t share them with anyone. Your conclusions will be wrong, because they will be based on woefully inadequate information.