I 25M own a house. I worked hard for this and saved for years to be able to afford a down payment on a fixer upper. I then spent every free second i had for over a year fixing it up. Im proud of my achievement and want to keep everything pristine because i poured my literal blood sweat and tears into it. My gf lives with me and pays rent to help with the expenses. I am going on vacation for 5 days with my parents, i invited my gf but she couldnt get the time off work unfortunately. I told her this months in advance. At first she was fine with this. Now she has invited her mom to stay with her while im not there because she says shes afraid to be alone, without asking me. I am uncomfortable with this, because i dont really want any guests in the house for a whole week while im not there. The bigger issue, is her mom smokes inside her own house and its disgusting. Im worried she will do that here and ruin my house with smoke and floors with ash. I brought this up to her and suggested that she could go stay with her mom for a week while im away, since she doesnt want to be alone. This turned into her screaming at me for over an hour, crying to her mom on the phone, and claiming my house is hers too. Am i crazy for not allowing her mom to stay in my house while im not there? I understand she does pay rent, and am fine with her mom visiting while i am there, but not staying for a week while im not there.