Hi Kyle, I used to have major issues with my erection and have managed to come good. A couple of thoughts come to mind:
Firstly, it is totally normal for your libido to wane with respect to your long-term partner. I am sure you know that men are not wired to be monogamous from an evolutionary point of view. That explains why we love pornography, specifically because our brain loves to think we are procreating with lots of perfect women to create lots of perfect offspring. Happy Days :-)
If you masturbate to pornography too much, two things happen: you use up your sexual energy, which you could "channel into" your real-life partner.. and your she becomes progressively boring to you, because you are spoiling your brain with all these perfect women. The solution: masturbate as little as you can, ideally *not at all*!
Interestingly, the trouble is that men are thought to be wired to orgasm frequently, because the quality of our ejaculation-ready sperm deteriorates after about 3 days in our testies. Frequent orgasms (most often through masturbation) therefore keep the quality of our sperm high so we are more effective at procreation... but I digress.
Secondly, regular exercise is not enough. You need to do stuff to raise your testosterone. That means lifting weights (big 'compound' lifts – look up a site called stronglifts) or bodyweight exercises at home to grow your muscles (look up the armstrong pull-up program). This will kick off a virtuous cycle of better physique, more confidence, better performance in bed, more sexual appetite and so forth.
Thirdly, 'vitamins and minerals' also isn't specific enough. Take a look at supplements like arginmax, aminoexpert vigarin and amitamin m forte. These improve your circulation and treat Erectile Dysfunction in a natural way. I have tried them all and my overall experience was best with amitamin m forte. It's top quality from Germany and includes pine bark extract, zinc and lots of vitamin B. Since I started taking this 8 months ago I have not had a single issue erection problem. In fact, my girlfriend sometimes gets 'scared' ;-)
Fourthly, explore each others' fantasies to keep your sex life interesting: BDSM, toys, role-play... whatever. And communicate! My marriage broke down, because I did not speak to my wife frequently and openly enough.
You can do it Kyle. Start lifting those weights today and don't give up. You are not alone. Keep us posted!