Can't get hard with my wife

Hello, I'm new here, name's Joel. History: am in my 60's & married to same lovely woman for 41 years & am retired. I've fapped a couple times a week for decades but this past year I've found I seldom am able to get hard enough for penetration even when my wife gives me a blowjob (just short of cumming). We usually are making love twice a week and I can almost always cum but for some time now it's been in her hands (still relatively soft) and this is the case even though most often I have taken PDE5 inhibitor drugs such as the blue pill, etc. On the other hand, when I masturbate, I usually can get hard even w/help from drugs & definitely with the drugs. By the way, I've been using Wellbutrin for mild depression for 10 years but no other prescriptions that are known to cause ED.
Wanting, I think, to 'affirm' my manhood, I've found I'm masturbating (though seldom to orgasm) and/or fondling myself sometimes numerous times each day. Example, I may be shaving and I often began stroking myself and often am able to get a solid erection, especially if I use a lubricant. I feel I've become somewhat obsessive about it, partly because I think I feel more 'manly' if I can get a solid hardon despite not being able to do so with my wife. Regarding 'porn' - I've used it occasionally over the years but mostly not, trying to avoid generating any reliance on it and instead use my imagination, often even while making love with my wife.
Interestingly, if often feels better when I stroke myself than when my wife does or even sucks me. I realize I've done a superb job training my cock to respond to my hand but have unable to maintain the joy of sex I used to have with my wife. My wife is I think good looking even at our age, our relationship is great and she's typically sexually very accommodating.
Has anyone had this kind of experience and if so has anyone resolved such a problem as I've described - by doing a 'NoFap reboot'? If so, I'm looking for any tips I can get that might help me better understand what I'm dealing with. It may seem obvious to many, but none are so blind as when we look at ourselves.
I'm very open to any questions and thank you for any help!

 

Hi D.J.; thanks for responding. Not that it's being questioned, everything I said in my original post is absolutely true; am reaffirming that and now will add to it . But to respond to your questions: "Are you excited or not by your wife? And, do you use anything when you masturbate to help you? Do you feel addicted to masturbation?". Despite wanting very much to be excited by my wife, I find these days it's as though my body, especially sexually, becomes 'numb'. She's tried harder this past year to get me excited (like sucking me probably several dozen times since this past January compared to one dozen times the past several years) and of course being very patient with me. In fact when she's 'stroking' me, aside from nuances, her grip, etc. is similar to my own. Again, this despite our really great relationship on virtually all levels. Regarding using anything to help me when masturbating, I've used porn only a couple times the past 6 months, otherwise relying on fantasizing about my wife or other women in our neighborhood. I'm ADHD and so even fantasizing is somewhat difficult for me. Lastly, 'do I feel addicted to masturbation?'; well, yes, kind of. I am slightly less numb to the touch of my hand versus my wife's hand as I know the nuanced moves that work, but really it's become compulsive these past few months, in part because I have lots of time on my hands (only the wife and I are here at home) and because dang it, it feels good. In all honesty I've for some time viewed it almost as self-medication.
I'm seeing more and more that a 'reboot' is likely the answer, if there is to be an answer. I've never ever talked or otherwise communicated anything like this to anyone and appreciate the existence of this forum for sure and am happy to hear from anyone. Again, thanks for your response and questions.