Lie is a grave offence. It is basically a sin, and every sin has a corresponding punishment.
Do different then talk different. Denial is a form of lie, especially if it's done with conscious intentions. Denying a relationship is very much insulting for the other party base on public's judgement. Denying a relationship is equivalent to lying to other people about the relationship. And a relationship built with lie (as a starter) is definitely not good. A building built with the wrong materials for foundation is as weak as a match-stick-tower; one blow and it'll definitely fall. But what if a liar lies for a liar? Well, that's a different issue. Liars like liars. If liars build their relationship with a lie, then I guess there's no irony in the picture!