For some reason, I find it entirely plausible that Harry would end up engaged without actually knowing how it happened. I liked seeing him inexperienced and a little confused, pondering about what the “dreams” meant and who to turn to:
These new dreams were about neither the Killing Curse nor Voldemort, but Harry still couldn’t talk about them. Not to Hermione, though she would no doubt find the meaning in a book. Not to Ron, who would likely recommend he visit St. Mungo’s, or Hermione.