People so often focus on the sex, as it that’s the issue. Sex, or lack thereof is a symptom. It signifies that something else is going on. Generally, a distancing between the couple.
Watching porn puts more distance between you two. He may be jerking off to it, and not really have much left when you want him. He may also be comparing himself to the beautiful, hard porn actors, and getting depressed when comparing himself to them.
However, I’ll bet there’s something else going on with him. Maybe a lack of a job, or he’s not doing well somewhere, or trouble with his relatives. I don’t know. It could be anything.
And between you two—obviously there’s tension. This can’t be recent. It must have been in the works for a while. Maybe there was a precipitating event (for us, it was the birth of our second child), or maybe it just started happening without noticing.
People are telling you to dump him, and that’s one way to go. However, if you love him, that’s hard. Therapy is another way to go, to try to identify and repair the damage. Or to help you part in a mutually agreeable fashion.
Whatever. I wish you the best.