@Chet31 it was explained.
Masculinity how they judge marriage potential in their culture.
I don't know anything more masculine than defeating a Hard Shelled Dragon.
Incidentally Feminine Battle Potential Max is defeating a Cthulhuoid
@8man According to the person who provided an explanation on the upcoming chapters in the previous one's comments, she's 16, someone else was saying 15.
Either way, apparently that kinda bothers him a bit and she just gets a "Sure, but only when you're a bit older" after he finds out.
@Landale Funny, I also find that the prospect of a 35 year old marrying a 15-16 year old bothers me ever-so-slightly; Kind of puts a damper on the series knowing that, to be honest.
I like to think that, in her mind, there couldn't have been any motivation for him to fight something so tough other than proving himself worthy of marriage. Really, there are other sources of food and materials.
fantasy setting or no, at least the main character doesn't seem to be a pedophile (so far). Seriously, if the girl was just a few years older, I don't think it changes anything.