The MC was still 14 at that point, almost 15.
Since Melissa seems younger than the MC from their introduction, when big bro is talking about Melissa being gorgeous, it’s a 20 year old man talking appreciatively on the sexual charms of a 14 year old girl.
Now perhaps in the game setting that’s considered appropriate, but to me, gross gross gross gross.
Edit: Okay, apparently Melissa is older than the MC, although I have to say she seems younger to me throughout the game so far.
Less creepy, but still gross in my opinion.