A person is likely to be afraid to make a commitment if they aren't themselves feeling stable and strong and have an overabundance of resources that already allows them to take good care of themselves and others. People generally respect others too much to make a commitment that they don't believe they can stick to.
Commitment phobia is usually seen where one of the parties does not want to get know by friends or relatives. This is because too much involvement with them makes a breakup difficult. He should also be seen to get involved in your life as you do the same.