Not only can the relationship between parents and children change during the teen years, it should change, it has to change, and it's likely to change whether you want it to or not. As children enter their teen years, they begin to build their own identity. It's a process, and it's not easy or quick; while adolescents will spend a number of years developing their new persona, the first stage is knowing what and who they are not. In the family situation, this usually translates into, "I am not a child," and "I do not have the same ideas as my parents." Teens feel a need to emotionally distance themselves from their parents to prove (to themselves, peers and parents) that they're no longer dependent on you. They'll often discourage displays of affection or care, especially in public. They'll want it to be clear to all that they have different likes and dislikes (in fashion, music etc.) and also different values and priorities than their parents.
Another part of growing up is that teens turn to people outside the immediate family for friendship and guidance. They will spend more time with friends and be more concerned about what their peers think. They'll look for leaders or role models as they begin to explore the possibilities the future holds for them. They're not rejecting their parents but rather looking beyond the familiar.
Parents need to be prepared to renegotiate their relationship with their children as they grow and mature. You need to provide your teens with opportunities to make their own decisions and take responsibility for their own actions. Just as when they learned to walk and often fell, your adolescent children will also make mistakes; the important issue is to continue to be supportive and available. Although the interim teen years may be difficult, most young adults want a positive relationship with their parents.