Sources and references for: Family Guy Sex ; Why do men look at porn

Question:

I don't understand male sexuality. We are a newly married family and I'm just starting to get to know his personality, character and eccentricities. I discovered that he was keeping a couple of video footages while he was having sex with a prostitute. It was a hidden videocam and the woman of course not aware. the other one is he was taking video of a woman who wears sexy lingeries (they were like shooting different underwears). when I confronted him about these he told me that they are friends and they are just having fun. but I don't want to start a fight so I just stopped talking about it. Then another thing happened. I discovered that he is continually collecting porn images and videos online. in fact he has a collection of them. I don't understand this guy I married.

He talks to himself when he goes out of the house to smoke but I think he doesn't know that I know. since I could see him from our kitchen sometimes.

Please tell me about this behaviour. I want to understand him. and I love him. Why does a married family guy want to look at porn?

Sources, references:

2. Which infidelity makes you most jealous, by Achim Schützwohl.
3. The clinical experience of Gunborg Palme, certified psychologist and certified psychotherapist, teacher and tutor in psychotherapy.