Where we part company with Lynn is that we let our perception of events color things and believe that when Anthony was stampeded into proposing, it was because Warren was trying to break up the monogamous pairing he and Liz had. Like Adam Savage, Lynn rejects our reality and substitutes her own. The rule as howtheduck formulated it is as follows:
Relationships only end when one of the partners is caught cheating on the other. If there is no cheating, the relationship is still on. The exception is if one of the partners is a Patterson. Pattersons do not cheat, but are allowed to date multiple people at the same time. For all non-Pattersons, dating someone else is cheating.
This means that since Warren was not caught cheating on Elizabeth and since she, as a Patterson, is allowed to date multiple partners, that she and Warren were still dating up until she got the token that said that she was taken. Where things fall apart is that even Inman would agree with our premise based on what he saw. Good thing for his need to worship Lynn that he uses her press clippings as canon.
Given that Lynn is so inattentive that she forgets the names of important characters like "Wrong" Girl Thérèse and that she thinks that this failure is a charming and funny thing instead of an indictment, she'd laugh off the baffling to her statement that what even her fans saw as Liz going from one bad boyfriend to another before finding safety with a plausible cipher with a perky exhortation to not overthink things.