Harsh as it sounds, no one should be "everything" to you except you. Someone can be "almost everything" to you, but you have to protect yourself. You have to keep something of yourself FOR yourself so if things come to a bitter end, you have something left. You need to gather your wits and get to know yourself all over again. When you can live comfortably by yourself, then you are ready to live with another person. But think of it as an emotional three-way. There's you and yourself (who are always together) and the third party who you HOPE will always be there but who you can live without if you have to. It doesn't sound like the romance novels describe it, I know, but the romance novels are so seldom right.