Rob Lowe and Sheryl Berkoff have been married for 21 years in a place, Hollywood, that's notoriously unforgiving on celebrity star nuptials. How do they do it?

First off, Rob Lowe celebrated 23 years of sobriety in May by sending a tweet out that reads:

Celebrating 23 years sober tonight. #ItWorksIfYouWorkIt

— Rob Lowe (@RobLowe) May 11, 2013

But not only that, Lowe is celebrating his nuptials with long-time wife, Sheryl Berkoff.

The two celebrated their 21 years of marriage by traveling to Rome in April this year, where they were snapped engaging in a little PDA on the streets.

But all has not been perfect for the couple since they got married in July 1991.

Lowe was infamously featured in a sex tape with a couple of different women in 1988, one of whom was revealed to be underraged at just 16-years-old.

The other was 22, but the timing of the tape's filming was tough.

Lowe was campaigning for Democratic Presidential candidate Michael Dukakis, and it was filmed before the Democratic National Convention in Atlanta, Georgia.

Lowe claims he did not know one of the women was 16, and it as confirmed later he met them at a bar.

After the damage to his reputation settled down, Lowe mocked himself in two different SNL hosting gigs.

But the sex tapes happened before he was married. Unfortunately, there has been some scandal with the 21-years-married couple though, too.

Jessica Gibson, the 24-year-old former nanny for the Lowe and Berkoff, made 12 allegations involving sexual harassment claims and labor-code violations.

Another ex-nanny was accused of falsely claiming to have had an intimate relationship with Lowe and also repeatedly expressing interest in Lowe, claiming Lowe sexually harassed her and that Sheryl Berkoff was an abusive employer.

Lowe filed separate lawsuits against three ex-nanny's accusing them of breach of contract, defamation and intentional infliction of emotional distress after spreading "malicious lies" about the couple.

Both lawsuits by the former nannies and the counter-lawsuit by Lowe were eventually dismissed in Santa Barbara court in May of 2009.

But the Rob Lowe and Sheryl Berkoff have been married or 21 years despite all these troubles, and judging from their Rome pictures, they're still going strong.