Simon Helberg Simon Helberg

Which Big Bang Theory guy will be the first to walk down the aisle? If you'd suggested Howard to Simon Helberg four years ago, he wouldn't have believed you.

Nonetheless, the wannabe ladies' man and coddled mama's boy is taking a big step on Thursday's episode (8/7c on CBS) when he proposes to gal pal Bernadette (Melissa Rauch).

"He's growing up!" he tells "The most amazing part is he found a great person as opposed to a prostitute or a mail-order bride. ... He ended up being in the healthiest relationship of all these people and moving the farthest along. That is pretty shocking, isn't it?"

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— may seem abrupt, considering he had trouble spending a night away from his mom just six weeks ago, but Helberg thinks it's the right time."Somehow it feels logical and earned because I think the writers have paced everything so brilliantly and the dynamic between everybody — it just makes sense at this point," he says. "You don't get a lot of backstory into what clicked, but they have these moments where there's a fight, as people have. You work through that and you see them together again. ... I think it's clear that these characters really are in love with each other, so I don't think it's totally necessarily to go through the wheels turning for Howard in terms of why now and how."The proposal, which Helberg describes as "simple and sweet," is also a complete surprise to the rest of the gang. Everyone else is caught up in rumors after Sheldon (Jim Parsons) and Amy (Mayim Bialik) decide to conduct a social experiment by spreading gossip. "It's a restoration comedy where there are these woven-in streams of gossip that are kind of corrupting everybody," Helberg says. "[The proposal] caps it — this moment of truth among all these lies. You kind of find out as [the episode] goes along who he's told and who he hasn't and how it affects everybody. It's really well-constructed."One person who remains out of the loop by episode's end is Howard's mother. But fret not, the unseen Mrs. Wolowitz will get her say in the season's penultimate episode when Howard tries to get her blessing. Naturally, she has reservations, which feeds into Howard's possible case of cold feet.

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"[That episode] deals with 'when is the wedding,' 'how is that going to affect him and his mother,' 'is this the right time for them to follow through with it?' It'll be interesting to see how he handles the fact that he can't hit on girls anymore," Helberg says. "I think this is really him holding his feet to the fire and forcing him to grow a little bit, which are always my favorite moments with him — those small, small inches towards becoming a better person, a more mature person."However, it's the fact that Howard is such a mama's boy that Helberg thinks he actually wants to settle down. Underneath all the bravado and cringe-worthy pick-up lines may be a true romantic at heart. "Having not had a father figure and having a mother in this unhealthy, symbiotic, bizarre relationship — as much as he talks about sleeping with girls, I think he probably is looking for a real companion, a future wife and mother," the actor says. "He puts on this front of being a ladies' man, but it's really because he's trying whatever possibility there is. Most of them are strikeouts. Until now. "

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Helberg — who will live-tweet the episode ("I'm practicing. I only talk now in 140-character answers.") — says there is "no wedding this season, unless they suddenly spring that us on." Executive producer Bill Prady has already said that the two will probably wed eventually, which Helberg hopes is the case. "I have a great affection for them together. Bernadette really gets him and [vice versa]. Will they get married next season? I don't know. I hope they end up together no matter what."The only question bigger than when and if the couple will get married: What kind of ring did he get? "Well, you'd have to ask the prop master! I don't know the cut," Helberg says. "There's a reference to it not being huge, but it seemed nice. He did well."