Orlando, Fla. ? To be an astronaut, you have to be the best of the best.

In NASA’s own words: Failure is not an option. That’s why psychologists say Lisa Marie Nowak may have taken rejection harder than most.

Some experts say that her case illustrates what could happen to anyone driven to extremes by love and jealousy. Others say the bizarre story suggests an underlying psychological problem that somehow went undetected by NASA and the military.

Agency officials said they try to determine whether astronauts have emotional problems before they ever begin serious training for a space mission.

“We screen astronauts with a series of psychological tests when they are first selected as part of their medical exams,” said James Hartsfield, a NASA spokesman.

But psychologists say people don’t go from being stable individuals one day to potentially violent attackers the next. Whatever was happening with Nowak had been simmering for some time.

“People just don’t snap; there’s often a buildup that others may not be aware of,” said Carolyn Stimel, a Tallahassee, Fla., psychologist and director of professional affairs for the Florida Psychological Association. “Jealousy and, in particular, sexual jealousy, can be very intense, and often there’s a combination of factors that combine, and people begin to act out in really stupid ways.”

Even so, Stimel said, such actions don’t necessarily suggest an underlying psychosis. Any of us could have a meltdown under the right circumstances. “I think everybody can get to the point that they’re overwhelmed and strung out and not thinking clearly,” she said.

Anthony Selvaggio, a professor at the Reformed Presbyterian Theological Seminary in Pittsburgh, has counseled many members of his church on the destructive side of love. He warns that unhealthy relationships can develop in any work setting.

“Love is such a core human emotion, and it’s really one of the most powerful emotions that we have,” said Selvaggio, who has written a book about love triangles and other marital woes. “It’s very easy for love to become an obsession, and once that happens, you begin to rationalize” very irrational behavior.

Once a person starts down that path, no amount of education and professional accomplishments can keep them from spiraling out of control.