If you say that you don't feel excited about your relationship... that is going to drive him further away. If my girlfriend said that to me, I would take it as a sign that our relationship is ending and that she doesn't want to be in the relationship much longer. I don't think you should say that (if you want this relationship to strengthen).
What you should say is what you want and need in the relationship. And you are going to have to figure out what you want and what you need.
- Do you want to feel more connected to him?
- Is there something you need from him to feel more connected?
- Do you want the relationship to get stronger but need a little space for now?
- Do you want more time with him? Do you need a romantic time with him away from the arguments?
You should tell him any of these things, they send the message that the relationship is important to you and give him an indication of what you need.
The long distance thing is difficult (I have been there). Feelings ebb and flow over any relationship, being apart makes these feelings and the insecurities around them more intense. But basically communication in a relationship is the same.
Tell him the relationship is important to you and that he is important to you. Then tell him what you want or need for the future.