@Talismaster
Well, they aren't wrong for the most part. Many manga (especially with the drama tag) play on this trope quite often. Likely because it is really easy to do with the common character set the MC/FMC usually have, which is either they are very dense, have dangerously low levels of self-esteem (like you need to go and see a therapist low), and/or swear to the church of non-commitment for some pointless or unknown (if any) reason. "Playing hard to get" is one thing (and I personally dislike this kind of stuff), but just not doing anything, even by "accident" (unintentionally), is what leads to NTR with the best friend.
Now, if the best friend is the worlds best wing-man with his own love interest, that is different and is very welcome. But best friend who is just waiting there to start shit and cause drama and NTR can go fuck himself.