Ok ok ok I had to come back to this thread to tell you about Season 2 of Mushoku.

The entire fucking season is about the MC overcoming their erectile dysfunction. That's it. That's the season. All of it. The entire character motivation of the season is having ED and not being able to get it back because he doesn't trust women after his first time went so badly wrong (the aforementioned jumping on him while he said no dozens of times, which ended with her running away the next day when he loved her) and the entire basis of his ED is that he needs to be in a relationship with someone he actually has real intimacy with and has built up real trust with.

That's it. That's the entire season. Episode after episode about erectile dysfunction.

Oh and they still have to solve it in the end with magical viagra juice.

This show is unbelievably stupid and definitely problematic at an elevated level but it's also not Shield Hero. I do think however it is trending towards a harem, a sort of Edward Elric meets Sword Art Online harem meets sexual harrassment.

tl;dr: MC gets ED from being traumatised by girl he loved that kinda forces him into sex when he didn't want to then runs away giving him huge abandonment issues. MC pursues a multi-year journey of study at university to cure ED, with the cure being real intimacy, real trust, and drugs.