Bill Gates spent one weekend a year with his ex-girlfriend under an agreement with his wife. Here's how to know if that would help your marriage, according to a therapist.

• An interview from 1997 revealed Bill and Melinda Gates had an agreement that allowed Bill to spend one weekend a year with his ex.
• Monogamy exceptions can be worked into an otherwise closed relationship, according to therapist Jennifer Mann.
• Clear guidelines for a monogamy exception are crucial to make it work.

A 1997 interview with Bill Gates recently re-surfaced, in which he revealed he had an agreement wife his wife Melinda, permitting him to spend one long weekend a year with his ex girlfriend in her beach house.

An agreement similar to Bill and Melinda Gates' may be appealing to otherwise monogamous couples who do not want to be explicitly open or polyamorous.

Jennifer Mann, a therapist and advisor for the Hope for Depression Research Foundation, told Insider before agreeing to such a set-up, couples have to align on the intention behind the agreement and the terms of the monogamy exception.

New sexual experiences can be great for a couple, as long as you both are on the same page

According to Mann, couples may add small exceptions to their otherwise monogamous relationship for many reasons, including making space to explore new sexual fantasies or partners.

Regardless of why a couple decides to add these exceptions, Mann said communication is key.

"If the couple is looking to strengthen their relationship through adding new experiences or people into their monogamous relationship, factors such as open communication, consent, and trust play a large role in making this shift a success," Mann said.

Whether it be a weekend with another lover or a month of sexual freedom a year, agreeing on the exact terms of the exception is crucial. A lack of consensus could open you and your spouse up to problems with trust down the road, Mann said.

If one spouse doesn't want to be open, an exception policy may not be what you marriage needs

Mann told Insider while negotiating a monogamy exception agreement into your marriage is perfectly doable, being on the same page about it is key.

If one of you is hesitant about opening the relationship in this manner, it could create bigger problems in the future.

Instead, if there are any disagreements, a couple should go to a therapist to develop solid groundwork for the agreement to make sure everyone is communicating their excitement and reservations.

"If there is one partner who is resistant, most likely this will cause additional stress on the relationship and lead to challenges that the couple will need to face to make this agreement work in the long run," Mann said.