They don’t have to give you reason to be private and you don’t have the right to give them a hard time about it.The only reason you may need to get worried is if you don’t trust your partner…in which case talk about it, don’t argue about it.
So your partners is keeping things from you? Well,that’s their prerogative. Are you quite sure you told them absolutely everything? The fact that they are in love with you does not mean they have abandon every last shred of personal identity.
Don’t be offended if they want space routinely. Maybe your partner wants to be alone when worried,busy or tired. It may not be about you,its just the way they function. There are times they want to be with friends and if you deny them that, they feel trapped. There are other times your partner wants to be with people that share the same interest and you following him around, asking tedious questions will not be fun. Truth is that its not about you, its about them losing themselves in an activity. It might be therapeutic for them.