I can't speak for the commenter, but many people (arguably, most?) manage to work around their differences to fit into society, if not make a relationship work for at least a while (see also "masking").

But anecdotal (friends, family, colleagues, myself), these coping mechanisms aren't permanent; masking constantly once you're living with someone else is pretty much impossible, fatigue/burnout kicks in often in people's 30s, and a lot of coping mechanisms people learn as kids are no longer effective or desirable as adults (often known as neuroses). Then there's attachment issues, also picked up as children. These may apply to everyone, but they're exacerbated for people with personality disorders, mental health issues and/or neurodiversity.

Figuring out what are "built in" / genetic / medical conditions, unhealthy coping mechanisms or trauma responses is a long journey that a lot of people are going through.