Season four of 90210 is all about "transitions," Gillian Zinser says, as the characters we've followed for years are growing into themselves, taking on various adventures in the world, figuring out where their lives will take them next.

Except for Zinser's Ivy, that is. She has already established her position in life, dedicating it to taking care of husband Raj.

"Ivy is in a completely different world from everyone else," Zinser told me over the phone. "She's struggling between finding a balance between her marriage and living for herself. What makes her happy? What does she truly want to do?"

Those questions do seem a bit more pressing than what kind of party Naomi will next throw.

When Ivy and Raj got married, they did so with an understanding that an "expiration date" was attached to the relationship, Zinser explains. He was sick. The concept of forever was actually not abstract. But now Raj's cancer is in remission and Ivy is questioning whether she fell in love with who Ray brought out in her, as opposed to Raj himself.

"There's a bit of romantic confusion," Zinser says and 90210 viewers know why: Ivy seemed taken with photographer Nick last episode. What can we expect to go down between these two? The actress teased:

"A triangle will form that will test Ivy's devotion and dedication to Raj. They will re-examine their relationship."

Starting tonight? Tune in and find out. The gang heads to Las Vegas this evening. Watch the new episode promo HERE and visit TV Fanatic soon after it airs for a detailed review.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.