Relationships change over time because each party involved also changes. The person you were and the relationship you had at 12 is not the same at 30 and that is to be expected. An entire life has transpired between those years, life which includes the addition of new friends acquired along the way. People who share very specific moments, experiences in our lives, friends who serve as a witness to our evolution.
The frequency and dynamics will definitely change over the years and that's okay. Emotional Maturity is to no longer have the unrealistic expectation that one person is going to provide everything for you or that the friendship will stay the exact same over the years. When you were 12 you may have had one best friend, someone who you shared all of your secrets, spent all of your time, included in all of your activities. But as adults, with complex lives and layered emotional spaces coupled with varied 'emotional and energetic growth rates' results in relationship changes and that is okay.
For example I have a friend who I met summer before senior year in high school. We attended the same college and spent practically everyday together. Our paths changed after graduation, she got married and began her career and family whereas my path took me out of state for graduate school twice, internship in NY, fellowship in Barbados, collected a few passport stamps across the globe, started a business, etc. Through all of those years there were years we were not in contact, but when we did and do reconnect we pick right up. Catch up on all of the life that's transpired, travel down memory lane and laugh. We are a witness to who we were and how far we've come.
It is not necessary to end a relationship because it's changed. The same way it's not necessary to destroy all tokens when a romantic relationship ends. These relationships are moments in time. Friends may move from inner to outer circle and that is okay.
There may come a time when you may need to formally close a friendship if the person is not respecting certain boundaries and that is okay as well. - Misha N. Granado, MPH, MS