For me personally, nope. Wait 2 years more, make it 20 and 25, then i think its more appropriate. I mean.. the 20 y.o will have their young adult brain that (should) understand consequences and (should) not being controlled by the older party, esp in decision making.
I don't need flashy characters,, and this story is such a beautiful one with great characters development. Glad i pick this up, cry along throughout the chapters, and be happy in their end of journey. Simply masterpiece.