I'm 25 and haven't had sex in 2 years. 2 years ago I had sex with one girl 3-4 times which was shitty.

Now I started having troubles keeping my erection hard rock when I'm masturbating while fantasizing or watching porn. I get hard all right but after a few minutes my erection gets like 70% if I don't touch it constantly. Is this normal?

I remember 1-2 years ago I would be rock hard all the time, even with just looking at a porn thumbnail or thinking about some fetishes...

Am I bored with masturbation? Is this because I haven't had sex for long and I need bigger stimuli then fantasy and porn?

Maybe low testosterone? Clogged arteries? I remeber few months back I was one month on an animal fat free diet and my erections got so much stronger... But maybe that was because of the beets/spinach I was eating every day (both increasing nitric oxid)...