Paul advised the unmarried Christians that if anyone is unmarried but hasn't yet reached the age of marriage and they're passions are controlled, it is better to remain single(v8) because then your only interest is to please the Lord(v32) instead of worldly things(v33).
In verse 9, he says, if they're passions burn for each other and they are not able to behave properly, in self-control of their passion for each other, then it is better they marry than risk fornication and fall into sin(v2).
I would like to add that for those thinking of marrying in their teens it is better if they both are determined to wait until they are matured and ready to marry, having their desires under control until then, but that's rarely the case. So it is always better to wait until you are capable of living on your own having finished your education before thinking about finding a spouse. But it is no sin to marry the one you love before that(v36). But it is more responsible and wise because then you will not be burned with all the anxieties and hardships involved in marriage and the world for a man in his teens.