His parents moved in three days before the engagement, is this how it's going to be?

This is not just about suitcases in the spare room. It is about a fundamental shift in your life happening without your consent, and your partner deciding that your home is a negotiation between him and his parents where you are not at the table. Selling a house and saving money are practical concerns, but dropping that reality on you three days before an engagement treats your shared life as an afterthought. If you stay silent now to keep the peace, you are establishing a precedent that major domestic decisions belong solely to your partner and his family, and that your role is simply to adjust. You need to speak to your partner directly today, before the temporary arrangement hardens into permanence. Tell him plainly that you understand the financial logic of selling their house, but springing a permanent houseguest situation on you without a conversation broke your trust. You can say something direct like, we are building a life together, and making major living arrangements without my input is not how a partnership works. The cost of raising this now is immediate friction during what is supposed to be a celebratory time, and you will likely face immediate pushback, guilt, or accusations of being unwelcoming from his family. But the alternative is worse. If you do not draw this boundary before the wedding, four months of living together will stretch into years, and extracting yourself from a joint household after the ceremony is infinitely harder than setting expectations now. Make it clear that you need a firm timeline for alternative living arrangements once the wedding is over, and pay close attention to whether your partner defends your right to be consulted in your own home.