Games where you can play through and only pursue one love interest (who is not a blood relative) from beginning to end. I am not including games where you automatically sleep around but then choose one later. Only games where you can choose to be with one person. (and obviously they are only with one person - no NTR, netorare, or girl on girl - I may include games with a non-optional threesome, but I will make note of it.) If you know of something that should be on this list but isn't give me a shout at PixillinsLists@gmail.com
Some games aren't available on Itch.io
This isn't meant to be a monogamous game and I can't swear to it working with each of the ladies, but I do have a save where I've only done anything sexual with Darci, so it might be worth a try.
This is not my favorite game. The "game within a game" aspect just didn't work for me and I didn't enjoy the time spent in any of the Eternum worlds. However, I think you can go through it with a single Li. I have a save where it's just Annie and the game hasn't forced me to deviate from that.
There are lots of possible paths and endings for Leap of Faith, there are also tragedies and sad bits but, if you can get through it the CeCe path is ultimately the most satisfying in any AVN I've played. (Not recommended if you're in a bad place.)
You travel to Egypt with a girl you've always had a crush on, her boyfriend, and a woman she's trying to set you up with. You also meet some new people while you're there. According to the developer, there are 11 different possible endings, and only one of them involves two girls.
Early in the story you are reunited with your childhood friend and crush Maria. You are given opportunities and even encouraged to move to more poly relationships but you can just stay with Maria with no problems.
Few meaningful decisions, most of which are about sex but a monogamous path is pretty easy in this one. You're asked once if you want to sleep with other people and once if you want her to and as long as you say "no" both times, you're golden. (At least so far).
I'm adding this provisionally because it's far from over. It appears that you can pursue a solo path, so far, with Eliza but it's not easy. There are a bunch of other women who you have to bat away constantly, over and over again - who just do not seem to take the hint no matter how many times you reject them. Eliza is, by far, the best girl though so it's worth it - as long as the developer doesn't fuck it up.
You can pursue a monogamous path with any of the girls. I assume you could do some sleeping around, to a point but it's not a harem game. You can't have them all. There is one point in some of the story lines where you can sleep with an older woman as a way to get her to help your Li but that is optional.
It's like walking through a minefield, the game will repeatedly try to get you to cheat, share your wife with other dudes, or engage in threesomes but it is possible to get through and only have sex scenes with your wife, Katherine - who is one of my favorite characters and should be enough to keep any guy happy, all by herself.
There are plenty of opportunities to sleep around in this game, but there are also solo paths where you only have sex with one Li. I highly recommend the Mora path (the freckle-faced, red-haired Uber Driver).
