A game not yet already mentioned off the top of my head is
Deliverance (by 1Thousand). The MC is a capable gumshoe dealing with unusual going-ons in his city. The MC is already married at the start of the game and there are several ways on how the game progresses. I don't want to spoil things too much but there is indeed a sharing route in which the wife is shared with others (and usually unbeknownst to the potential partner) and done with the
full knowledge and consent of both the MC and the wife. The MC and wife will continue to communicate and love each other in the story, and the wife will never humiliate the MC. This is consensual sharing from the side of the married couple. (It should be noted that the game has a lot of content for routes that doesn't involve sharing as well so no one should be feeling left out.)
On the development side of things, the dev -- 1Thousand -- has laid out the story for his inaugural game (with things already planned out) and has really been on top of things. Thus, it's not a game where it will continue in perpetuity. It should be wrapped up this year. There won't be prequels, sequels, or any kind of spinoffs. However, 1Thousand has done a great job creating an adult game with an actual plot with wonderful accompanying scenes. It is a visual novel but it is
not nukiage. Recommended! Have fun!