This really depends on what he's doing during "alone" time. If by alone he means hanging out with a hooker and an eight ball of crack, then you should probably worry. However, in most cases guys just need a little time to themselves without any responsibility or intimacy or talking or any of that business.
I think this may be similar to when a girl goes out for a girl's-day-out. We all need space from our better halves from time to time, not to worry.
He's right on this one!
In fact, there is a theory that if a man doesn't occasionally get alone time that he won't be able to love his partner to his fullest. It has nothing to do with his mate, so don't stress it.
...is the same still true if he's using his alone time to watch porn and girls on youtube and facebook - even though he doesn't contact any of them?
that depends, is he still sexing her as usual? If so, why would she be threatened by the porn. Clearly, it has not had any negative effects.
I'd say that if a man isn't spending much time with his woman, the woman should probably get a mirror and ask herself "What's wrong with me?" I know with my ex girlfriend, I started to "neglect" her when she started gaining the pounds. Weight is key in any relationship. A woman MUST stay fit and tight, or she'll lose over to women 10 years younger.
Mitt Romney 2012!