I really think it's a personal thing for your happiness right? You seem happy to carry her memory and knowing that's exactly what matters to you. If others need someone around, or that you can share the future moments with, then you aren't lying about it being "forever" if you continue living life, life changes lots of things. Sharing that love with someone is huge, but they also wanted to be with you for it. They can't be, so if someone finds someone else and they want to walk through life together I'd like to think someone can find that.
Some are happy with the memory, and their values hold that they would never involve another. But others know that they needed each other to get through the good and the bad, and that person isn't here anymore. They'll never be the same as the person who is gone, but it doesn't mean having them in your life is a "failure" or "betrayal"