They're not going to be her

Just realized that even if somehow I end up in a relationship with a girl (this is a completely fictional scenario that will likely never happen in the real world but let's just go with it anyway), I won't be able to make any kind of physical or mental connection because they aren't her. They don't have her hair or eyes or smile. They don't give me the same slight feeling of warmth and comfort. It just won't happen. I can't get over it no matter how much I want to. All I want to do is talk to her again, in any way, it doesn't even have to be online. There's a crazy insane part of me that is desperately hoping to run into her again someday so I can express this because it really is ruining my life and I don't know what else to do.