How to get engaged to Hermione Granger

When Harry offers to help Hermione out by joining her at a quaint family diner, it's no big deal. But when he gets angered by her stupid cousin and decides to fake propose, it is. How far will they go to sustain their facade? And what happens when unwanted feelings start to blossom? This will be a romcom Harmony story. EWE. No Ginny/Ron-bashing. M-rating for smut in ch. 4 and up.