Dr Harley says that, whenever a spouse cites a need to move out "to get space" or some such, he always suspects an affair first, and is usually proved right. I don't have time to search for it now, but perhaps another poster will be kind enough to link the Q&A column in which he says this.
The biggest thing for me is that even when we were first dating my husband never really put me or our relationship first and he is a chronic liar. It has always felt like our family and relationship come second to his social life. He cheated on me when we were dating but never admitted to it until this last winter. He lies a lot and has always been sneaky about his phone, etc... Also, he says that he only started lying because of the way I reacted to him when he did tell me the truth but I think that is just him trying to manipulate me and make me feel bad because throughout the years I have found out about lots of things that he lied to me about when we were dating and I didn't freak out about things back then...I didn't even know that things were going on because I never thought to second guess him. Why would you need to lie to someone you say you love and want to spend the rest of your life with? He always seems eager to go do something with the boys but won't do anything with me.
The above is classic cheater behaviour.
He has no need to be secretive with his phone, unless he is doing something on there that he does not want you to see. You already know about his pornography habit, and it sounds to me as if he would not go to great lengths to hide it, so this is something else.
He vigorously guards a social life that does not include you.
He admits to lying to you about cheating when you were dating. Having sex with someone else while dating is not the same as adultery - but why lie about it until busted only recently? Because it's not the only time it has happened.
He is a liar who has a secret second life.
He is having an affair. He might be having it online. He might be having it long-distance. However he is doing it, he is having one. Ignore this fact at your peril.
What will happen if you refuse to believe the affair is that, having separated from you, he will soon introduce a "new" girlfriend to everyone -
but she will not be new. She will be the reason he left home in the first place.
Men who want to be married do not object to their wives wanting to be their recreational partners, and wanting to know what they do on the phone. Men who guard their separate social lives and "refuse to do anything with you" do not want to be married, because they would rather have the freedom to screw other people. It makes no sense that your husband has moved out after only 3 years, leaving his little daughter behind, just because you want him to take you out, give up his single life with the boys, and see his phone.
It makes no sense because he is having an affair.
Your husband is having an affair.