An open relationship is a relationship in which the participants are free to have emotional and physical relationships with other partners, often within mutually agreed limits. If a couple in a relationship like this is married, it can be called an open marriage.
Open relationship allows them to have more freedom within their lives tend to believe that participating in additional intimate relationships, with or without emotional attachment, makes them better partners to the people they are committed to.
Negative aspect is that, you open yourself up to feelings of insecurity, jealousy, and other negative emotional feelings. How would it feel to love someone, and run the risk of your partner becoming more attached to a one night stand or occasional fling, than he or she is attached to you? This could open up a whole in emotional turmoil.
Every healthy relationship involves plenty of trust, as well as emotional maturity. In any case, be glad you've got the opportunity to discuss the issue openly, and you're sure to make a decision that is best for all involved.