He only hung out with Stephanie for like a year or so, and clearly even by his own recollection was all up in his own head back then anyhow/dense af. I don't see why anyone is making a massive deal out of this. He was distant with her and her needing someone to be there for is why she thotted out in high school. MC wasn't childhood friends with her like he was with his best bud.
He wasn't hanging around with Stephanie from start to end. He played around for maybe a couple years as a kid with Viki, until she started getting crazy jealous the MC wouldn't look her way. He was well over 40 when he died, and had been obsessing over another girl that time.
How hard is this to get that someone is going to forget a lot of details by that point, especially when he kept obsessing over a handful of specific details/memories?
The game is literally called "Twisted Memories"
of course his perception of the past is going to be screwed up. MC even admits to himself how he has a lot of things all screwed up from hyperfocusing on his own warped perceptions of people. Like what are some people so pissy about?