Viagra can wreak havoc in some relationships.

Byline: Peter Mucha

Three years ago, Viagra was approved by the Food and Drug Administration, and ever since it's been hailed for its effectiveness in helping men with erectile problems.

But as therapists and divorce lawyers have learned, the blue diamond-shaped pill occasionally has a disruptive side: It can rekindle tensions between couples, leading them into therapy or divorce court.

"It changes the status quo. This wreaks havoc in some relationships," Philadelphia area sex therapist Nancy Gambescia said.

Often in cases of impotence, a couple's relationship drifts into a fragile truce, with the partners avoiding sex and even talking about it. Then along comes Viagra.

"It has the ability of throwing the relationship out of balance again," Cherry Hill, N.J., psychotherapist Greg McGreer said.

That can happen in some surprisingly different ways:

Scenario 1: He won't use it. The first battle involving Viagra can be over whether a man will take it.

As many as 30 million American men have had some erectile dysfunction, or ED, according to…