A strong friendship doesn't need daily conversation or being together. As long as the relationship lives in the heart, true friends never part.
Just because someone's life doesn't revolve around you doesn't mean that they don't love you and care about you. Friendships change over the years, and some years you may talk to a friend every week, while other years you may only talk once a year. Friendships change based on a number or things; change of jobs, a move, family changes... Just because you don't see each other as often as you would want doesn't mean the friendship ends. You can still love people and be friends no matter how often you talk or get together.