Should I let my daughter go away for the weekend?

My daughter is 16 and a half, she has left high school and is currently studying at the community college. She has entered the "adult world" yet is only still a teenager. Her boyfriend, who is 19 is a lovely boy and her father and I see no problem with them dating or the age gap.

She has recently asked me if she can go away to Melbourne with her boyfriend in about a months time. (We live in NSW) while I believe she herself thinks she s ready, my parent side cannot help but focus on her age.

I know nothing dangerous would happen and it would only be for a long weekend away, but still feel torn in my decision. Please help