I feel like I am already losing interest in my wife 1 year into marriage.
What don't you like about your current wife?
I don't think she is mature enough to understand my feelings.
Communication is the key to a successful relationship, so you should talk to your partner and get on the same page as her. It is better to resolve the issues you have now rather than hurt her feelings later on.
How will I know that she can understand me?
You will not know if she can until you try. It is better to try in the first place than not try at all. I am sure she will do her best to understand where you are coming from.