Ken Baumann Ken Baumann

Getting married just because you're expecting a baby from a one-night stand is not exactly the best reason to say "I do." Or is it?

Last week, Ben balked at his father's suggestion to wed Adrian (Francia Raisa) on The Secret Life of the American Teenager (Monday at 8/7c on ABC Family). The teen, however, will have a change of heart on Monday's episode when the two go in for Adrian's first sonogram.

"He definitely is not decided for sure," Ken Baumann, who plays Ben, tells "I think [seeing a sonogram is] an overwhelming experience for anyone, especially for a teenager. It's times like that where he realizes the gravity of the situation. Ben's kind of a neurotic guy. He's always going to have the 'grass is always greener' portion of his brain ticking."

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But is it ticking enough for him to act on it after seeing his child for the first time? "There's a very expensive object in play," Baumann teases. "It can be a ring. ... It definitely has to do with Ben."Marrying Adrian might be — as her father says — the practical thing to do, but Ben's heart still lies with Amy (Shailene Woodley

), who's still at a music camp in New York. After breaking the news of Adrian's pregnancy to her two weeks ago, Ben has heard squat from Amy. But she has to come home eventually."We'll see how much longer she tries to avoid him. The radio silence speaks volumes," Baumann says. "It would be pretty tough for him to date her [while he's expecting a baby with Adrian]. It'd be hard for all four of them."

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The fourth is, of course, Ricky (Daren Kagasoff), Adrian's ex and the father of Amy's son, John — also the result of a one-night stand. Ricky jets off to New York to see Amy on Monday's episode, much to Ben's chagrin. Though Ben's irked, Baumann says the teen won't try to get back at them like he did in the Season 2 finale when he slept with Adrian, given the new circumstances."Before [the show goes on midseason hiatus], you'll see Ben make some decisions and resolve some things for himself," Baumann says. "He's going to be a dad so he's trying to be responsible. I think it's great. This season has been my favorite arc for Ben and it's just going to get better. I'm very excited. He's young, but I think he's going to make a great dad."Would he also make a great husband?"Why not?" Baumann laughs. "He's a good guy."