It’s not about the porn
I was having a conversation with a friend about his dating history. He was talking about how when he was young in his dating experience, he felt like he was boxed in by all these rules -- don't cheat, don't use porn, don't even look at other girls. It wasn't that he wanted to do all those things, he just felt like the rules were controlling how he showed up in the relationship. He compared that to the expectations he has in his relationship now: trust, honesty, compassion.
Rules Control Behavior
The thing with rules is they tend to be tied to our most basic needs. We don't turn left on red lights to protect the drivers on the road. Rules exist because they are non-negotiable due to the risk they pose to life. We respect these rules because of the protection they provide, and in that way the rules control our behavior.
Now think about those rules that are "made to be broken." Don't drive before you get your permit. Don't ask out your buddy's ex. Don't talk about money, sex, politics, etc. Rules that we consider more flexible tend to be rules that don't actually protect our health, but instead protect the ruler. Think about it this way: not debating politics protects the person who doesn't want to debate politics.
This isn't to say you can't express yourself to your partner or create rules for your relationship. But consider this example. Your partner says, "You can't watch porn because it feels like cheating." Your partner is establishing a rule that controls your behavior so they can protect their feelings. Now, you care about their feelings -- presumably because healthy companionship comes with some empathy -- so you may be motivated to follow this rule because you want to protect their feelings. This is good for you, and it's probably pretty difficult.
If you agreed that watching porn felt like cheating, then you'd probably be very happy in this relationship never watching porn. But, if you were only ever doing it to protect your partner's feelings, you might come to develop some negative feelings about it. Maybe you'll grow to resent them for asking you to make such a sacrifice, particularly if you're unsatisfied in your sexual relationship. Or maybe you'll just wish they trusted you enough to not have to establish a rule like that in the first place. No one likes to be controlled, even if they do love and care about the person doing the controlling.
Expectations Create Connection
So let's go back to this example. Your partner says, "You can't watch porn because it feels like cheating." You know you partner is trying to protect their feelings, but what are they? Are they worried you might cheat on them like their high school sweetheart? Are they morally opposed to the porn industry? What are the feelings they are trying to protect?
Let's say it is about when their ex cheated on them and it made them feel like they couldn't trust their own instincts to know if someone was being faithful. Wow that sucks. It sucks that someone broke your lover's heart and they feel like they should have been able to see it coming. Your lover is someone who deserves to see something like that coming, don't you think? Your lover does deserve honesty -- even if you were to feel like you wanted to be unfaithful.
That's how you get to expectations.
Your partner feels insecure about your porn use because they don't expect honesty when it comes to thoughts of being unfaithful. Now, this isn't every person who has ever told their partner they can't watch porn, but it is an example of how you can get from a rule -- which might feel controlling or unsustainable -- to an expectation. And an expectation is a shared value. So now you're protected against feeling like the rule is unfair and you're more connected to your partner by establishing this shared value.
Making a Shift
It’s not that there’s anything wrong with having rules in your relationship, but if they become an issue, you can create some space by trying to shift the focus of the rule to the feelings and values that accompany it. Remember, this isn’t about alienating your loved one for having their fears, it’s about holding their concerns in a different way so you can both be comfortable.
Let's put this into a nice little list:
What's the rule meant to protect? What's the feeling behind the rule?
Where does the rule come from? What does it mean to them?
How can we create freedom and opportunity around that value, without controlling each other?