The most important thing is that you think carefully about what you’re afraid of and then talk about it with your partner. It makes no sense just saying: I feel jealous, not even knowing why.
You should be more clear and think carefully, what exactly are you afraid of. We are all afraid about changes but fears and other feelings can change. And if they do, you need to be flexible about changing. So if you are planing an open relationship: Set up your arrangements and agreements Think about it very carefully and talk to your partner about every doubt and wish