While I certainly respect that some fans don't want this anime to get too dark (I myself share the same sentiment to some degree), I'm not exactly sure why the addition of child abuse (it wouldn't have to be sexual, by the way) would be making this show melodramatic.
I mean, we already have:
1. A teenage boy who cosplays as his deceased childhood female friend, including cross-dressing.
2. An (unsuccessful) attempted rape scene.
3. A hikikomori male lead that had quit school for a long time.
And all of the above were presented pretty seriously, in my opinion.
I would never underestimate Okada's ability and tendency to broach taboo and/or very touchy subjects, and with a certain maturity as well. Wandering Son and True Tears speak loudly to this, imo.
Thankfully, Okada is generally very good at this.
