Any sane know-it-all will tell you that trust is the foundation of a good relationship. But any Hollywood insider will tell you that pre-nups and hush-ups are what really keep the love alive.

Guess which route Jennifer Lopez is taking.

Forget about trusting the one you love. In Tinseltown, you have to make sure the one you “love” keeps his mothereffing mouth shut. That is if you’re used to going through relationships like the rest of us go through bathroom air fresheners.

You know, like our girl J.Lo.

On the gajillionth major relationship of her life, the singer, 43, has been all over town for the last year with 25-year-old boytoy Casper Smart, a dancer and choreographer from her tour. She is reportedly head-over-heels in love. And so soon after her third marriage fell apart! Such a divine miracle.

That’s why she must have felt it was important to have Smart sign a confidentiality agreement -- just like all her other employees have to do. It’s a simple contract that covers all interactions her workers have with her, either on or off the clock, to keep them from selling their stories to the highest bidder.

That was probably even more important for Casper, seeing as how he obviously has his share of off-clock interactions with Lopez. Oh well. There goes his book deal and Oprah interview.

Even so, he said he was happy to sign the agreement and would've done it even if he didn’t work for the pop diva. According to a source, “Jen loves him even more for that.”

Ah, Hollywood, where love is a many splendored and contractual thing.