BTW, if you're really worried? Add a subplot. Whether it's something to do with side characters and their story and how it impacts the boys, or some other kind of small plot coming in to throw wrinkles in things... a subplot is really great for expanding things in unexpected ways. I've sat down to write many a 10k fluffy bit and then had it develop plot and end up surprisingly over 30k accidentally. Just one extra thing to resolve or work out helps tons!