>>279674242 (OP)>Why is it always like this?It's not. There are plenty of romance stories for girls where the female lead isn't exceedingly pretty, you're just predisposed to noticing it less because "plain girls" still have a baseline level of anime character attractiveness, and/or often come off as homely cute to guys.
As for why it's comparatively less common for romances aimed at boys to have a handsome male lead, it's because more of them are targeted at a male self-insert fantasy where the protagonist can find love with a hot girl even if he's super ordinary or an outright loser. At the same time, it's not uncommon for romances aimed at girls to target a female power fantasy about being a princess; i.e, the female lead finds love in part because she's cute/beautiful and incredibly desirable to the hot guy(s).
Again, these aren't universally true, both demographics have works swinging from one side to the other; this is all speaking in a very broad and relative sense.