Perhaps you've reached a phase of life where you find that pornography isn't stimulating. OK, now that I've stated the obvious...
I wouldn't presume to know exactly what is happening for you. I don't think there's anything wrong with losing interest in pornography.
I've gone long stretches in my life where I've not looked at pornography because I've lost interest. Actually I don't own any pornography. I know that many people would find that odd in this day and age that a man wouldn't own any pornography.
For me, I have known people in the porn business. I'm a psychotherapist intern. I work with people who suffer from sexual compulsion. I work with people who have been sexually abused. I've had friends who were exploited sexually for the profit of others. I've had friends who have prostituted themselves to get by. In my opinion the porn industry isn't a pretty business. It exploits the people who are in the images created. So many of the actors and actresses were abused sexually as children. Many are sexually compulsive. Many are drug addicts who believe they don't have any other way to make enough money for their next high.
So, when I think of all of this stuff, I can get disgusted with porn. There are times where I find it hot though, sort of a forbidden fruit. During those times I'd like to believe that the actors and actresses are doing this because they truly want to do it and are well-adjusted people who aren't being exploited. I'm a guy and I'm turned on by imagery and I have hormones.
So, I guess I have a love/hate relationship with porn.