How long have you been with him?
What are your ages?
Has he always been like this or did this start at some point?
Thank you for that additional info.
What do you mean that 'he was always content being on his own'?
How often do you see him?
Do you only see him when he wants to see you? What does he do when you want to see him?
Have you talked to him about it? if so what was his response?