Relationships for teen daughter?

Any other parents out there that can help me out on this, I would appreciate it. Do you feel that limiting your teen to just dating and no long term relationships would hurt them in some way? I feel that by limiting the "long term" relationships would deter my daughter getting attached so much to a guy that she would not buy the "but I love you", "I am in pain -- I need it" kind of crap ---- I tend to see girls that date guys for 3-6 month in length tend to be “more” ually active because they feel in their undeveloped mind that they in a grown up relationship and that is what grownups do ---- but they are just kids ---