GARDEN CITY, N.Y. (AP) _ An hour after Roberta Burke's longtime partner downed Viagra, they engaged in some red-hot, long overdue sex. Within two days, he was gone _ on the prowl, she says, for more conquests.

Now she's suing him for $2 million in palimony, and her lawyer says the lust drug should come with a warning.

``He's dating lots of women,'' Dominic Barbara said. ``He now thinks he is a young man in the body of a 70-year man. The man even had a quadruple bypass last year, for God's sake.''

It's exactly the kind of trouble some columnists and sex experts have been predicting ever since Viagra hit the market seven weeks ago. With impotent men suddenly reinvigorated, infidelity was sure to follow, they said.

``I don't want to sound like a Jewish grandmother who said I told you so,'' sex adviser Dr. Ruth Westheimer said. ``But I've said that unless the pill is coupled with education and sexual literacy, I predict a lot of troubles.''

Ms. Burke, 61, claims the impotence drug led Francis Bernardo, 70, to infidelity, destroying their 10-year relationship.

A phone number for Bernardo could not be found Friday. He was served with the court papers in New Jersey, where he has a new girlfriend, according to Barbara.

Ms. Burke, who did not answer phone calls seeking comment Friday, said in court papers that the retired construction executive had been impotent for four years. After he swallowed the tiny blue pill, they had intercourse early this month for the first time in years.

She described it as ``wonderful.''

But two days later, Bernardo walked out of the couple's luxury condominium. He left a note saying the relationship was over and boasting of his renewed vigor, according to Barbara.

Sex researchers have warned that many couples may not be prepared for the sexual changes that can accompany the use of Viagra. Older women, in particular, may be unable or unwilling to match their partners' heightened interest in sex.

``I had a couple come in where he's demanding sex since he went on Viagra, and she's not up to it,'' said Dr. Domeena Renshaw, director of Loyola University's Sexual Dysfunction Clinic near Chicago.

Although the drug changes relationships, it does not lead to infidelity by itself, Renshaw said.

``If you're a cheater, you're going to cheat _ with or without Viagra,'' she said. Viagra ``just gives people a newfound confidence to follow their basic predilection.''

Ms. Burke, who is divorced, met Bernardo in 1988 at a country club in Hilton Head, S.C., where he owns another home. She soon moved in with the widower.

``She stuck with him when he was having his sexual problem,'' Barbara said. ``She loves him and she'll take him back at any time.''

The lawsuit, filed May 15 in state Supreme Court in Mineola, is both a palimony and a divorce action. In South Carolina, the couple are considered married under common law.

If New York courts refuse to recognize the common-law marriage, she's seeking payment under the palimony lawsuit.

Raoul Felder, a New York City divorce lawyer, says it would be difficult to prove Viagra destroyed the relationship.

``It's a long stretch,'' he said. ``Why don't you blame short skirts or perfume?''