I think we are going off topic here a little.
everyone has different views on porn, and that is absolutely fine. It does however, depend on the type of porn and if it has a negative effect on a relationship.
Personally, I have always watched porn, and when not in a relationship has become somewhat routine for me. I am however as careful as I can be about the type of porn I watch and am fully aware it in no way reflects what happens in real life, it’s a fantasy for the most part.
OP, how is your sex life? If your OH is watching porn INSTEAD of being intimate with you then it becomes a problem. The lying about it is a red flag to some degree, but he will also no doubt be hiding it through shame or guilt, or to make you feel less insecure, which ironically has had the opposite effect as you now know he’s been lying about it.
however, Facebook ads of scantily clad woman is not porn, it’s algorithms designed to put ads in front of a certain type of internet user based on their search history. Yes, it could be because he has been on porn sites, but as you have firewalled them this is unlikely and could be because he is looking at ‘manly ‘ stuff online, which to be honest could be absolutely anything.
Not all men watch porn but the majority do. The latest figures show that 59% of men aged between 18-50 have watched porn in the last month, and 40% watch it on a weekly basis. For woman it’s around 23% and 16% respectively. I’m not sure if this is uk or US figures btw.
if a male says he doesn’t watch porn, there is a fairly high chance he is lying. He might not be addicted and he might only watch it a few times a month, but men get horny and when there is no other option to offer that release, whether that be because they are single, or their partner is away or ill, porn is really one of very few options: most Men need visual stimulation to get erect and to be able to have a release, whereas a woman needs physical touch like her hands or a vibrator etc.
IMO, and this is ONLY my opinion, if a male watches porn, when in a relationship, it has no bearing on how he views his partner. It does not mean he finds her unattractive, or no longer fancies her, it is a visual stimulation which results in a physical release. Porn should not and can not be substituted for intimacy with a partner in a relationship and when this happens this is when it becomes a problem.
I know this scenario is a little different, but how many woman would agree not to use toys or masturbate if their partner made that a rule, even if they went away for a week for work etc? I bet most on here would say they could easily refrain , but I’m not so sure if the reality would be the same.