The clothes are bugged. When you remove them, they're left on the floor, but in some cases they're duplicated, and in some cases, if you remove them, turn around and wear something else, it may happen that you end up with your 3d model wearing both, while on the inventory you're not shown the one you were originally wearing.
Happened to me and I had to start a new game becauseI couldn't remove the towel. Having the shirt, skirt and towel all at the same timemade the rendering pretty weird too.
Some suggestions for the next version, should be pretty simple to implement:
1 - Add an option to reset clothes. Can even be the current "give up" option, as long as it doesn't fuck up happiness too much (Basically, just remove all clothes from everywhere, and then set the clothes for model & inventory);
2 - Add a difficulty setting. It could either change the rate at which happiness is gained/lost (i.e. gain more/second, lose less/second for easier lvls) which is probably the easier option, or change all thresholds/requirements as well as stepmother's movements etc, which would probably be a pain, or even locking happiness at a certain lvl/range (i.e. can't fall below XX%, or stays locked at XX%, changing that percentage at predetermined in-game events).
3 - Add an option to erase all data. If the save gets unrecoverable, it's a pain to find the folder in AppData, then there's a file in a subfolder etc. Having a reset would make it a lot easier for us to test stuff. Bonus points if it can also export the current save data to a zip file or a folder, and re-import it.
As for a not-so-simple suggestion, but in the long run this is the most important as it will save you from a LOT of pain with bugs: Have a single source of truth for stuff. From what I saw in the clothes bug, you probably store the clothes in more than one place. That's usually what causes this kind of problem. And we can only "remove" what's listed in one of those places. If you check for duplicate clothing items and use the same variable for putting on/removing/inventory, we'd probably be able to fix it by wearing the bugged item and removing it again, but that's a bad way to do it. If you sync both variables on load, that's better, but still not ideal. If you have a single variable telling what Samantha's wearing, this problem would solve itself. Sure, Unity may have some render bugs, but a simple reload should fix that, provided you reset what's being rendered on load. If you have the same data in multiple places, not only you have to always have multiple identical changes, you risk race conditions creating different states, and thus have to add checks for consistency. It's A LOT easier to have a single source of truth.
Not sure how experienced you are with programming, but if you're not familiar with that, just search "race conditions" and "single source of truth" (And maybe "async programming" and/or "parallel code", should return some neat stuff about how to safely code for parallelism/multi-threading/asynchronous stuff. If you want more, "data consistency" could be another search, but this will probably lean towards synchronization for distributed database servers, as well as client-server, like mobile or web apps that keep a local copy of the data). BTW, if you're interested, personally I'd have an object for Samantha (Could be an Object or any other Data Structure, like a Named Array, a Hashmap or whatever Unity favours) with EVERYTHING directly related to her, from her Happiness to what clothes she's wearing to her coordinates/position, her name, her hair color, her "level" or whatever you call it, any actions that may be active, stats, personality traits, ongoing event(s), everything. And I'd always refer everything else to that. That prevents a TON of bugs and makes it a LOT easier to keep everything organized and consistent. I'd even store what missions/events she may have completed in there, but that means removing an event (Or mission or whatever) may cause bugs with old saves, so if you'd rather store whether she completed each event in the event's object/data-structure, that's fine, but make sure that you don't store that same information (Or something that depends on that like how many events/missions she completed) anywhere else, because if you do, consistency bugs WILL appear sooner or later, and you WILL need to add checks to deal with that, possibly even a way for the player to trigger a consistency check, and that's always a pain that causes tons of bugs.
That's it for suggestions/tips/etc.
Now as for what really matters: The game's great, you're doing an amazing job. Thanks a lot for this. Sorry if my suggestions are a bit too much, it's just that I really like what you're doing here, and wanted to offer what little help I can, especially considering I've seen a lot of race-condition/parallelism/async/consistency bugs, and noticed all the same signs when playing the game. Hopefully it saves you some pain chasing down bugs.
Again, thanks for the game, and keep up the good work, you and the game are both awesome!!!