Melissa Rauch and Simon Helberg Melissa Rauch and Simon Helberg

For The Big Bang Theory's Howard (Simon Helberg), proposing to his girlfriend Bernadette (Melissa Rauch) was just half the battle. Unfortunately, the newly engaged couple still haS a long way to go before they tie the knot — that is, if they ever tie the knot.

"There are some other things that they are going to discover about each other that they're going to have to work out," series co-creator and executive producer Bill Prady told reporters at Comic-Con Friday. "They never talked about what kind of life they wanted to have together: where they were going to live, what they were going to do, whether they wanted children. Howard got so caught up in, 'Oh my God! I love someone who loves me back,' that they haven't had all of those conversations."

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But even before the lovebirds plan their future together, Howard's ego will take a major hit when he finds out his bride-to-be is the real breadwinner of the house."Bernadette is going be continuing in her job at the pharmaceutical company and earning more money than Howard," Rauch said. "It will definitely be an obstacle that they will have to overcome."

Helberg isn't optimistic either. "I can't imagine that it's going to be a smooth road to that, if it ever gets to that, because he might be the only one who shows up," he said."I think every single thing he's going to face is going to be a complete disaster."

But above all,  the biggest roadblock to their domestic bliss will be Howard's demanding mother. Rauch sounds ready for the challenge. "As we know, you don't just marry somebody, you marry their family, and Howard's family is very intense," she said. "It should be neat to see that relationship build between Bernadette and Mrs. Wolowitz."

Complicating things further is Penny's maybe-hookup with Raj (Kunal Nayyar) that we saw in the season finale. "I know we woke up together, but nobody knows [what happened]," says Kaley Cuoco. "So I think that will be interesting." Penny will have to deal with the aftermath of (possibly) sleeping with her ex-boyfriend's best friend, all while helping Bernadette plan her big day. "I think I'm going to be the maid of honor; I think Bill Prady said that," Cuoco said. "Her best friend is marrying his best friend and I'm sure there's going to be a million issues and problems."

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Although Leonard technically had a girlfriend at the time, Johnny Galecki thinks it will take time for him to accept what happened and really move on. "I don't think he handles it well. I didn't handle it well personally when I read that part of the script," he said. "I'd be surprised if Leonard is speaking to Raj when we come back."

In turn, Leonard's beef with Raj will also cause trouble for Sheldon (Jim Parsons) and Leonard's friendship now that Raj and Sheldon are living together. "I would imagine that he will have some major things to say about how it affects this newfound relationship he has with Raj as a roommate," Jim Parsons said. "Honestly, he could give a damn about Penny and Leonard, and if they have any troubles. It doesn't bother him at all, unless it bothers him, which means it's got to affect his life."

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Cuoco and Galecki, however, are notably more optimistic about an eventual happy ending for Penny and Leonard."I'm definitely one of those people that thinks they've got to end up together," Cuoco said. Added Galecki: "I think they're the loves of one another's lives."

Season 5 of The Big Bang Theory premieres on Thursday, Sept. 22 at 8/7c on CBS.