I say it's his life! It's not as if they are married. Let him use whatever he likes. Now if my husband was doing it, I would want him to let me know so I could maybe buy him one that he could use. This way I still had an input in it and it would be easier for me to understand that way. In my opinion though, it's whatever he needs to do, but if things get serious, just be open about it. What women hate are the secrets.