How to tell my son she is coming?

Moving from dating to living together when your son is still asking every night for his mother to return means you are trying to rush a timeline he is not ready for. At eight, children hold onto the hope of parental reconciliation because the alternative feels too permanent. If you introduce a new partner and her child into your home while he is still actively grieving his biological mother's absence, he will view them as the obstacle stopping his mother from coming back, which will turn his heartbreak into resentment. You need to pause the plan to live together. You have only known this person for a month, which is a very short time to rearrange a child's entire living situation, especially when he is emotionally stuck in the past. Instead of jumping straight to a joint household, start with very slow, low-pressure introductions outside the home. Let them meet in neutral spaces for ice cream or a park visit so your son gets used to her presence as a friend rather than a replacement. You also need to address his nightly question with absolute clarity, even though it will break your heart. You have to tell him gently that his mother is not coming back to live in this house, using simple words that leave no room for false hope. This will cause tears and anger, and that is the cost of being honest with him instead of hiding behind a new family arrangement to avoid the discomfort of his grief. Let him process that loss fully before you ask him to welcome someone new into his daily life. Only when those nightly questions stop and he feels secure in your individual relationship with him should you talk about sharing a home.