Let’s clarify, it’s best to join a group travel trip for these reasons:

• Skip the planning and enjoy your time together.
• Travel strengthens relationships and ignites romance.
• It’s an excellent way to bond with other fun couples.  Find a new girlfriend or buddy.
• Eliminate ruining friendships by inviting other couples that may not share similar travel ideas.  Don’t find this out the hard way. 
• No worrying about what your friends want to spend on a trip, dinner, or activity.  You will if one couple can’t afford or doesn’t want to incur a cost.
• No waiting on other couples.  You can go at your own pace and not have to worry about keeping other friends happy.  No need to compromise on the schedule.  
• Let’s say your husband mountain bikes, but you don’t.  You can do another activity, like horseback with other new friends while he goes off on his own.