A bun is a great protective hairstyle for long hair. It protects the ends and length from damage and breakage. I am fine with my wife wearing her hair up in a bun or other protective style most of the day, as long as when it’s time for us to be intimate, all that hair comes down and I can touch and play with it.
You can even incorporate a daily scalp massage and brushing regimen to stimulate hair growth. I love to participate in this. If she’s really growing it out for you, let her do all she can to keep it healthy. If you need to look at her silky hair, take a few photos when it’s down.