• Penny and Leonard Wedding Teaser Trailer

Penny and Leonard Wedding Teaser Trailer (Photo : Entertainment Weekly )

After years of dating, Penny (Kaley Cuoco-Sweeting) and Leonard (Johnny Galecki) are getting married in the premiere episode of "The Big Bang Theory."

The lovebirds' on-and-off relationship is about to get officially more serious with a wedding ring on their fingers. When the smoke clears at the end of the first episode, Penny and Leonard will be in a long-term relationship that will shape the rest of the season.

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The relationship between the two hit a rough patch in the final episode of season eight, as detailed by TV.com. Leonard admitted to Penny that he kissed another girl in one of his trips but the two decided to get married regardless.

In an interview with EW, executive producer Steve Molaro tells us how Leonard and Penny's relationship mirrors the show's progress over the years. He reveals that the long-running sitcom is progressing in major ways and the same is true with Penny and Leonard. Molaro says that Penny believes that she can get past the infidelity shown by her groom.

She's fully aware of how long they've been together and she's sort of psyching herself up that the incident happened years ago. She thinks that they weren't even married back then. Penny seemingly takes the making out lightly, telling herself that she can get past Leonard's mistake and she wants to move forward.

The executive producer also notes that the relationship problems that their characters go through are a reflection of real life.

Molaro explains that Leonard, Penny, Sheldon, and Amy are like other people who go through rough patches in their lives. They, too, have a choice to either work things out or give up entirely. He adds that for the couples, there are things that need to get worse before it improves.

Watch the teaser video of the wedding below. You can also check out some of the images from the wedding at ComicBook.com.

"The Big Bang Theory" season nine premieres on September 21, Monday at 8 PM ET on CBS.