Betty and Veronica are friends in the comic. Their friendship is depicted with various emotions and experiences, sometimes they get along great and other times they have misunderstandings, but it remains a friendship throughout.
Veronica was indeed Archie's girlfriend in many instances within the comic. However, the comic often presented complex relationship dynamics, and there were also times when they weren't a couple. It all added to the interesting plotlines.
Since we lack the details of the 'Mona Darling full story', it's difficult to define who Mona Darling is precisely. She might be a protagonist in a love story, facing challenges in her relationship. Or she could be a strong - willed character in a thriller, fighting against some sort of danger. There are countless possibilities depending on the nature of the story.
Since we don't have much information, Veronica could be anyone. She might be an ordinary person whose story became significant in 2017 for some reason. Maybe she was part of a local news story, or it could be a personal account shared within a small community.
Another theory is that it might be a composite of several different women. However, historical evidence mostly points towards Lisa Gherardini. She lived in the same time and place as Leonardo da Vinci, and the connection through her husband's commission is a significant factor.