If you are feeling concern about losing time-I would suggest scheduling time.
If you are feeling insecure about the relationship and potential other partners-time to do some introspection on yourself.
If you are feeling uneasy dealing with "new"-face it and communicate through it-new always turns into old over time.
How to manage the issue depends entirely upon what the real issue is. Because what will help with one won't help with another.
"Love As Thou Wilt"