In 'Heart of Darkness', Elena (Nina Dobrev) initiated a passionate kiss with Damon (Ian Somerhalder) during a road trip the pair took together, but still claimed to be uncertain of her feelings for him.
In an interview with TV Line, Plec said: "As we've seen [with] Damon and Elena's relationship in the past, they keep being drawn to each other, but obviously there's something holding her back.
"Rightfully so in a lot of ways, because they've been through a lot together and not necessarily all good. As we get closer to the end of the season, really the key word is 'confusion' for Elena."
Plec also hinted that Damon and his brother/love rival Stefan (Paul Wesley) will begin to lose patience with Elena's uncertainty.
"The brothers have to decide if they're going to be okay with allowing her to think this through," she teased, "or if they're going to reach a point where the confusion becomes frustrating for them."
She confirmed once again that the season finale will see Elena make a definitive choice.
However, Plec wouldn't rule out the third option of an ending in which Elena "chooses herself", or a fourth in which she chooses both brothers.
She teased: "That would be giving too much away to rule out one of the three options. I guess there's a fourth option, which is, 'I choose both of you'."
Plec went on to back up Ian Somerhalder's recent suggestion that Damon and Stefan will bond in upcoming episodes, revealing that they will have a conversation about what Elena's choice means for their relationship.
"The conversation of what will it be like when she does choose is something that happens in the second to last episode of the season," Plec said. "It's actually a really introspective, nice and emotional moment between the brothers."
The Vampire Diaries continues on Thursdays at 8/7c on The CW. In the UK, the series airs on ITV2.
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Watch the promo for the next episode 'Do Not Go Gentle' below