I manually exited by choosing so from the pause screen and choosing 'main menu'. I quit right after the MC said "better grab that box before leaving for work". Literally after that dialogue, upon Emi having left a note. I then noticed the main menu had 'continue' greyed out, meaning it never once attempted to save. I had been looking for an icon to show it was saving or any text saying 'game saved' while playing, but nothing ever displayed, if that also helps. Windows 11 HP Elitebook laptop playing the game through the Itch.io app's full install of the game.
Edit: So, I just checked the save folder and there ARE saves there. THEN, I loaded the game up, and NOW the 'continue' button is pink and accessible. So, it appears the glitch is not a lack of the game saving, but a lack of the continue button being functional when returning to the main menu from the pause screen. Closing the game out and then re-opening it seems to fix it.
I just tried to recreate it and cannot get the glitch to recreate. So, it may be linked to the first time the game is played. Something may not be triggering it to register there is a save when going to the main menu after playing the first time.
Also, small feedback about text in the game... your words that are contractions (such as can't and 'won't) are insanely spaced after the apostrophes, displaying as "can' t" and "won' t". It is an issue throughout the entirety of gameplay thus far.

Edit 2 (critique now that I have finished the demo): A couple more criticisms. First, it is clear the art is AI, I suggest not using the pixel filter over it and just going for the smoother look. Just own into it and not try to hide it with a filter. It really is blurring a lot of the images that are not larger, such as when you are uploading the pics of your co-worker. They would look way better without the pixel overlay; and I say that as someone who prefers sprites to CG in most games. Or, make it an option to toggle the visual effect in the settings. I mean, it isn't even consistent; there are some places where the pixel filter is not used at all, such as the map, where the female in the thumbnail when choosing 'work' is smooth and not a pixel out of place, despite the man in the Mall's thumbnail being a mess.
Secondly, please move choice boxes way higher up on the screen. I have to keep restarting days because I am trying to click to the next text box when all of a sudden a choice comes up and one of the decisions' boxes is directly under my cursor, making me click it (such as the one on day three where the game lies and says there is an H-scene if you choose it when there isn't one). Either move the boxes, or include a 'back' button to go back in dialogue as many games have, please. Preferably both.
Third, on that same note of the scene... please make the text and on-screen visuals work together. If you soak her shirt it is NOT an H-scene and there is ZERO nudity, yet the option says "(H-Scene)" and the text that follows is all 'wow, I can see her nipples through her shirt' when she has a thick-ass bra showing through it and absolutely zero nipple or areolae of any kind. It is misdirecting to the player, conning them into choosing the act that is clearly the immoral one while offering no reward - despite one being promised - and just angering the co-worker. What you COULD DO is say 'POSSIBLE' H-scene in the option choice, then, when the shirt is wet, instead of detailing nipples that are visible when they are not, have the MC be like 'damn, I was hoping that would work better'. It will act as a sort of tutorial to denote that not all choices will have the desired outcome going forward and allow you to play with the options a lot more, widening versatility.
Another example of inconsistency with the art is the very last scene. Kana supposedly 'swallows everything' and was on her knees, but the picture afterward is her standing with stains on her skirt and thighs. Logically, - especially with how she has at LEAST double-G breasts - any stains would have been on her chest and never even seen her lower body. It greatly distracts from the immersion, breaking me out of feeling there and snapping me back to 'oh, right, I'm playing an AVN'.
As it is right now, I am intrigued by the story, but also turned off by the UI and pixel filter and annoying contraction issue with text. That being said, I also feel a lot of things could be slowed down to build tension and intrigue. Especially everything to do with Kana and Emi. We, as players, don't get to see any relationship build with Kana. We don't get to see the MC and her bond, but then she is suddenly agreeing to the pics and then jumping right to a BJ with very unrealistically little apprehension for someone the game describes as 'shy and innocent'. There needs to be a lot more scenes where the MC and her build trust while she remains hesitant before the BJ scene. As for Emi, they meet and walk to work on day one, then suddenly are acting like besties on day 2. It makes zero sense, implying that months have passed by despite the rest of the story between the MC and Mari implying it is actually just a day passing, and loses all value of allowing the player to feel they are accomplishing a bond with her.
TLDR: don't force your story to progress fast just to get to details and points you want to get to. Let characters develop and grow through interaction.
Also, I really thought the game would be far less linier, offering gameplay that focused more on stealthily monitoring the computers and digging for dirt while micromanaging time, similar to "Janitor of Love". I thought when we got the cameras it was leading up to such gameply elements.
Also, pro tip from a certified PC tech since 2003: there is no way he would have been locked out of Mari's PC ;) We can backdoor anything, especially as a sysadmin. Remote access is an easily acquired feature. As a techie I was like "why doesn't he just do this or this?" I get you are trying to push a plot for spying via the cam, but it resulted in making the MC look bad and ill-suited for his profession. Also, in that same scene, when Mari gets to using her toys, there is a flash of the previous fantasy of the MC taking her from behind first. It flickers on the screen for a moment before changing to Mari with her toy.