how do u feel about porn?

So my fiancé has been telling me that he has to watch porn to stop himself from checking out other women & fantasizing about them?? He's never been this way before.. He knows that because I've been thru so much, that I am insecure. But he "reassures" me constantly that he will never cheat.. But that he does fantasize about being with other women. This tears me up, every day. I love this man more than anything.. But this is getting out of hand for me. Especially because I'm home, & he'd rather watch porn than to be with me. How do u guys feel about this?? Do u let ur significant other watch porn, even when ur available??