Allow me to assist.

yumeship = yumejoshi (Japanese slang term for a girl who inserts herself into a fictional story) + ship (fandom term used to refer to two characters getting into a relationship) = the act of imagining a fictional version of oneself getting into a relationship with a character from a piece of media one enjoys

uncomfy/gen = uncomfy (you can guess) + /gen (tone indicator that means the previous statement is genuine as opposed to joking or sarcastic)

(by the way a tone indicator is a well-known sequence of letters appended to a text message to communicate the intended tone, like /s for sarcasm, /j for joking, /gen for genuine, etc., used to communicate through a text medium what would otherwise be conveyed through tone of voice. Traditionally they're appended to the end of a message, not used in the middle of a sentence. I've never seen a tone tag applied to a specific word before. The author also seems to be using it as an intensifier, which... huh?)

canon = (adjective, applied to a statement about a fictional world) confirmed in the text of a fictional work, or by the author of said work in e.g. an interview, as opposed to made up by fans (in this case, used rather disgustingly to refer to something that is true in real life as opposed to a fictional setting)

F/O = Fictional Other = Fictional + Significant Other

c.ai = character.ai = a website where users can converse with LLM chatbots that pretend to be fictional characters. Anyone can create and finetune such a chatbot (by starting with a blank slate character and interacting with it and telling it how it should act) then making it available for others to use, and a lot of users create chatbots that imitate real people. The website doesn't really crack down on this.

Essentially what the person who sent these messages has done, is gone to character.ai, looked up a chatbot that pretends to be a real Internet celebrity, convinced themself (I think?) that the real Internet celebrity was a fictional character (or at least could be thought of in those terms), talked to it until it told them that it was in love with them, concluded that the real person the chatbot was pretending to be was also in love with them, and confronted said real person with this information, expecting them to make the fictional relationship real. It's a textbook parasocial relationship, except for the part where the non-celebrity wasn't listening to things the celebrity was saying, they were listening to things a chatbot pretending to be the celebrity was saying.

Rather than responding, the real internet celebrity who received the messages took a screenshot of them and made a post conveying their disgust that any of their fans felt entitled to act that way, and a screenshot of that post is what you're seeing here.

This is just a screenshot of mental illness, you don’t need to know more than that