Deceit
Quentin Collins is an accomplished liar.
Unfortunately, when one becomes so good at lying that no one can tell when you're lying or not, people start not trusting anything you say.
(Quentin thinks that this is probably a very smart idea and that he should probably learn a lesson from them and not believe anything he says, either.)
At the moment, Quentin says he's in love with Amanda Harris.
(However, Quentin has also said he's been in love with Beth, and Jenny, and Rachel.)
Quentin also says that he is going to run away with Amanda Harris.
(Quentin has also said this to Beth.)
Running away from Collinwood is something, Quentin knows, inevitably needs to be done. He has a rather unappealing marriage in his immediate future, not to mention being indebted to a man who killed a close friend.
(Quentin knows that this isn't true at all, because even though Petofi made him do it, and even though he didn't hammer the stake through his heart, Quentin is the one who killed Barnabas Collins.)
In any event, Quentin thinks, there is simply nothing left to keep him at Collinwood at this point – except for the woman he loves,
(The woman he says he loves)
who is planning on going with him anyway.
(Quentin knows that this is his biggest lie. It's just a shame that he's lying to himself, and he's the only one who really believes him anymore.)
So, when Quentin decides not to tell Jamison that he is leaving, he knows that it is inconsequential. Jamison still is angry at him for marrying Angelique and not Beth
(Which Quentin did to save Jamison, because Jamison meant more to him than any woman did)
and probably wouldn't talk to him anymore, anyway.
(Quentin decides not to tell Jamison he is leaving because that would mean talking to Jamison, and if Quentin talked to Jamison once more he wouldn't leave at all.)