I don't have any dislike for the fact that the ROC is an independent country, whether my government diplomatically recognizes them as such or not. I'm just pointing out that, if a Taiwanese family invites you to dinner, they're going to be weirded out by you continually saying "Republic of China" throughout the conversation.
I have lots of Taiwanese friends, but I appreciate your concern. I do use 中華民國 when talking about politics or anything related to the government or cross-strait relations. If I'm talking about the island of Taiwan specifically, I have no problem saying "Taiwan".
Because all of them are actually from the island of Taiwan (not Kinmen or other holdings of the ROC), and they generally (and increasingly) do not want to be associated with "the Chinese": https://esc.nccu.edu.tw/course/news.php?Sn=166
"China" is a bad brand name nowadays. I really wish they could formally rename their country with a resumption of the civil war.
