TRAVERSE CITY, MI—Although both believe that a romantic affair would only complicate their daily interaction with each other, Troy and Tania Knudsen find it more and more challenging not to act on a powerful mutual sexual attraction, sources close to the married couple said Monday.

Troy and Tania Knudsen can barely keep their hands off each other.

"You can really sense that something is going on between them," said neighbor Lisa Eisennagel, who has known the Knudsens for nine of the 12 years they've been married. "It's so palpable, it's sometimes uncomfortable to be around them."

Friends who spend regular time with the pair have all noted the tentative glances, a tendency to linger around each other, and inappropriate touching.

"Tania hints at how she's attracted to Troy," said Eisennagel, who claimed to have shared many talks with Tania about her hidden feelings for her husband. "I'm sure he feels the same way. It's so obvious at this point."

But Tania is reluctant to act on feelings they both "might regret," according to Eisennagel. "Tania's always going, 'Is he thinking about me? Does he feel the same way?' I say, 'Why not ask him?' But she just turns red and changes the subject."

According to the Knudsens, their close shared quarters make even the smallest interactions both exhilarating and stressful. Earlier this month, Troy, flustered after catching a glimpse of Tania's cleavage as she placed a plate of waffles on the kitchen table, had to excuse himself to smoke a cigarette on the back porch. The couple's thighs touched briefly while watching TV on the living-room sofa last Wednesday, though both fought the urge to make eye contact. Likewise, the narrow hallway between the living room and kitchen has played host to some awkward, charged moments.

"I only have one more semester before I earn my physical-therapy degree, and this career change is important to me," Tania Knudsen said. "I also have  two young kids to consider. I can't imagine risking all that, just because I can't resist these urges."

She added: "Though sometimes it feels like I'm torturing myself."

For Troy Knudsen's part, the plumbing contractor said he often anguishes over whether his wife shares the same impulses.

"I have to share a bedroom with this woman for the rest of my life, so I don't want to do anything to make things awkward," Knudsen said. "I have a routine I'm used to, and taking it to the next level is not part of that routine."

"He said he often lies next to her, struggling not to kiss her," said longtime friend Ken Boehmer, who introduced the two in 1992.  "And one time, she bumped up against him in bed. I was like, 'That was the perfect opportunity, dude!' It just sounds like they're making excuses. We all wish they'd just fuck already and get it over with. If it doesn't work out, I think they could handle it in a mature fashion. After all, they're both 36 years old."

While some of the couple's friends believed the intense sexual tension and the nature of their relationship made succumbing to their attraction for each other inevitable, others said that it has gone on too long for them to relent. All, however, agreed that if they came clean with their feelings, they would at least both be able to get on with their married lives.

"If they're 'best friends,' as they put it, why did Tania wipe that barbecue sauce off Troy's cheek the way she did?" said neighbor Pete Lorenzo, who invited the pair to his annual Fourth Of July cookout. "And the way Troy wrestled with Tania for the last piece of bratwurst? Christ, get a room. Or just go home."