Fanning (or rekindling) the flame

"The mistake most couples or one person makes is they're so much in love with their partner that they assume the relationship will last forever," said Robert Billingham, an associate professor in Indiana University Bloomington's Department of Applied Health Science. "They don't think it is something they have to work on."

Human beings are not built from a biological standpoint for long-term romance, said Billingham, whose research interests include interpersonal relationships, parent/child interactions and the long-term effect of divorce on children. Biologically, the body chemistry that makes our hearts flutter is replaced after several years with body chemistry geared more toward attachment, he said. Couples, therefore, need to work at keeping the romance alive.

Here are some of the professor's tips:

• Date, find ways to spend time together to enjoy each other. "Individuals change. The relationship changes," he says. "This core behavior (regular dating, emphasizing the relationship) says, 'No matter what happens, we find time for ourselves, find time to celebrate the relationship.'"

• Make sure your children see the love. Parents spend 18 to 20 years preparing children to leave home. Parenting requires sacrifices to properly care for children, Billingham says. But investments in the relationship as a couple can benefit parents and kids alike, and make the "empty nest" seem not quite so empty.

"If the kids don't see an emphasis on the relationship, what we model is that the marriage isn't as important as work, sports or other activities. When they do see the emphasis, what we're modeling is that the marriage, the committed relationship is important. That's crucial because we need to teach our children that our relationships are more important than things like work, movies and sports," he says. "We do a very poor job of this in our society."

• It's never too late to rekindle love and romance in a stale relationship, suggests Billingham, but it becomes much more difficult if one of the partners has fallen in love with someone else and is experiencing a new round of attraction "hormones." If both people in the couple say, "I want to get this back on track," there's hope.

• Sex can make life and the relationship more pleasant. He notes that couples who are healthy and who can sustain an active sex life tend to live longer and be happier.

Billingham says that research indicates people who divorce experience poorer health and a diminished quality of life, so longevity can be worth the effort -- with the right partner.