Vow Renewal: Infidelity and Back

Out of all of the factors that can strain a marriage -- money, sex, monotony and more -- distrust may be the hardest to get over.

Dan and Kelly Gengler, high school sweethearts who eventually married, never imagined there would be a day when their union would be fractured by a broken commitment

The Genglers' love affair took off at full speed after their first date. The couple had their first child by their senior year of high school. Then, they were married in 1996, one year after college. They were still in their early 20s when Kelly became pregnant with twins.

"There wasn't really time for Kelly and I to talk or really do anything," Dan said.

While Dan found comfort and relief from the stress in playing sports with his friends, Kelly began to feel lonely.

She decided it was time for her to get a life outside the home and began a search for part-time work. When she began looking for resume Web sites, she ended up in a place she never intended to be.

"I clicked on a button. I didn't know what I was clicking on and I ended up in a chat room and kind of fell into a conversation with a man who I began an emotional affair with," Kelly said.

Looking for the support Dan wasn't providing, Kelly threw herself deeper into the relationship. By the time it became physical, there was no turning back.

"I left. I packed my bags and I left," Kelly said.

Dan said he was shocked by Kelly's departure. He felt betrayed and abandoned.

"She didn't care about her kids or about me anymore and she would rather spend all her time with this other guy. So I had to accept it. I just got mad," he said.

When it seemed as if all hope was lost for the couple, Kelly decided she wanted to try and make her marriage work. She suggested a retreat for struggling couples, but Dan wanted no part of it.

"I pulled the kid card on him. I said we have to be able to tell the kids that we tried everything before we called it quits," Kelly said.

Dan reluctantly agreed to Kelly's suggestion and in the long run, he's happy he decided to give their marriage another chance.

"We learned that we loved each other and that we're completely opposite from each other and that we just have to keep working on it," Dan said.

Kelly said she now realizes that all couples go through rough patches. She understands that it's the way couples react in the hard times that matters.

"All relationships go through stages. You know, there's the romance and then you have the disillusionment with each other. And then some couples fall into misery, which was obviously where Dan and I were. But you have to push through to get to the fourth stage of marriage, which is the reawakening," Kelly said.

As they look forward to renewing their vows with 125 other couples live on "Good Morning America," Dan says he's confident their special love is one that will last a lifetime.

"I can tell from high school to now, we're kind of learning more. But there's so much more to learn and it's going to take the next 50 years to learn it," Dan said.