Here are a few thoughts:
1. I think the MC and Anne should be able to set rules for their relationship under the right conditions. For example, if the MC and Anne agree to only do things together (MC participates or just watches) or only after telling the other one first and the MC sticks to that plan, then so should Anne. If they really love each other and have trust, then this will work and can lead to lots of hot scenes as they get deeper into exploring together.
2. Give the MC the ability to be more assertive in situations involving anne. You do a great job of letting the mc romance and be assertive with the other side female characters and they LOVE him because he is a great lover and the right mix of assertive/sweet. Let the MC tell anne about his conquests and take video/pictures/let her secretly watch without the other side chick knowing anne is watching. This should make him more attractive in anne's eyes and not let her see him as someone she can walk all over. Also, the MC has to have the right to call anne out/outright stop the situations where she tries to fuck him over in front of his face. Martin is the best example, there is no way in hell, unless you are on a pathetic, voyeur only cuck route, that the MC would ever just let his father fuck anne in his own house. Give us the option to go full alpha male on martin by knocking him the fuck out and then fucking anne in the shower while martin is out cold. Also, under the scenario where anne and ryan fuck after you told ryan not to, or if they lie to you about it after you watched them......you have to let the MC confront them at breakfast after overhearing their conversation or walk in on them if anne leaves in the middle of the night to fuck him. The MC has to be able to kick ryan out permanently and confont anne. A great alternative would also be for the MC to go and tell ryan's wife what happened and be able to fuck her and send ryan and anne video/pictures of the deed under the caption "this is what happens when you lie," or something like that. Don't make the MC be so passive and just take everything anne does.
3. Don't let everyone of anne's conquests have a massive dick or be some great lover. She should have negative experiences in the form of 1. a guy being a quick shot 2. a guy not being able to get it up (like and old guy such as the dr. or phil) 3. she should be treated harshly/rough trying to fuck guys like troy and she should not like the experience. All of these things happening would serve to make anne appreciate what she has in the MC and bring them closer.
4. Give anne standards. The thing I hate the most is that she literally is/will fuck anyone by chapter 10. fat, old, ugly....anytime and any place. Give her some self respect, or at least give the MC the option to become distant from her and outwardly focus on the other women like nicole, chloe....etc without respect for anne if she whores herself out.
5. For the endings, I hope there will be a happy path where the MC and Anne realize that they are enough for each other and decide to go monogamous. A happy path where the MC and Anne are happy together and have only occasional swinging/threesomes. A happy path where they have a trusting, completely open relationship but stay together and happy. A path where the MC leaves anne, who has become a complete slut, and the MC finds happiness by either falling in love with one of the side girls/becomes a player that fucks tons of the side girls regularly while anne ends up regetting losing the MC. A path where anne leaves the MC after the MC cheats/breaks her trust too many times.....she ends up happy with dre or as a single girl fucking whoever all the time, while the MC regrets losing her and is miserable. An ending where they break up and both are miserable and miss what they had.....leading to a sequel game where you have to win anne back.