Abstaining relates to ED. You dont seem the age where you'd be addicted to porn or anything. I don't have numbers but I feel generally people without ed can have sex at least every other day without loss of quality of erection. Up to a certain age. Masturbaring once a couple of days before might make your semen count low and have less sensitivity and take longer to cum, but I don't think it causes ED

 
I'd suggest to try pharmaceutical help (ie, Blue pill) or at least talk to your urologist.
Its a trivial solution to something that really haunts many men, with the only downside being the possibility that you might get conditioned to always take it and then will not be able to perform without it. But it seems like you're having problems as is so why not?  

 
Good luck!

It may sound like bro science but there were apparently studies done on this. Check out “More Plates More Dates” on YouTube on the topic of fapping. The studies found that testosterone will reach its height after 7 days of abstaining with a drop on the 8th day and continuing to drop until it normalizes. This, of course, influences libido, performance, and other hormone related functions.

I am about 5'8 and 165-170 lbs.. My regular blood pressure is between 125-80 and sugar around 95 (fasting)  If I don't masturbate for a week or so, I will start developing pain in my scrotum area. At 10 days I won't be able to walk without feeling the pain.. I have gone 10 days without a release just to see how bad it is, and it's pretty bad..

 
Not sure if you have any serious health issues, but what you are saying doesn't sound typical of our age..  

 
You probably should see a doctor.

I would say anything longer than 3 days is going to be diminishing returns -- unless you watch a lot of porn, that is mental and not physical.  You def need to try some ED meds to see if that will help.  They aren't popular for nothing.  

Do you think it’s performance anxiety or physical?  Either way, a small does of an ED med should certainly help.  Abstaining for any longer than 3 days should have, as others have mentioned, diminishing returns on the impact.  The other supplement I’d recommend is L-arginine.  It’s just an amino acid that you need anyway.

This is likely more mental than physical. If you can get hard while watching porn, etc and/or still have an erection at night or when you wake up, it’s definitely mental i.e performance anxiety. You’re right around the age where your prostate can begin getting enlarged - which can ad to erectile issues as it did with me. The blue pill plus not overthinking the whole thing got rid of my ED. Abstaining for longer than two days doesn’t do anything for me; in fact when I take off too long from sex, it takes a few frequent sessions days apart for my libido to get back into full gear aka ‘use it or loose’. The human body is very adaptable. If you train your body to think it’s going to have frequent sexual encounters, it will get itself up to speed just like your muscles do with a gym routine.

Jerk off.

I do often. If it feels good when your with provider why does it matter if you cum, or not? If the goal is to cum don’t jerk off.

I'm mid 40s and have always been one pop since college, but I can last 2-3 hours.  Due to this I have to book two hours and try to finish before the time is up.  I don't cum for at least three full days, but I try for five days for the best experience.  I've even used sleeping pills at night to help me doze off.  Better yet, just talk to your doctor.  Most of the time doctors don't have any issue giving Viagra.  

Try masterbating and edging yourself an hour or two before your session.  

If I jerk off, it gets me thinking about sex more than I usually do, and I am more prone to want it again soon. I can get hard again in about 10-20 minutes if I even get completely soft and come again within an hour or two although I tend to enjoy the afterglow from sex with a real lady instead of my hand. However, for me, coming is not the goal (as QueenBia suggests), intimacy is. Mutual oral and mutual masturbation give me as much pleasure PiV sex, even more if the oral is uncovered and the PiV sex is covered.  

Have you tried sildenafil (the generic name for Viagra)? I use it sometimes and not other times. It isn't strictly necessary for me, but it makes a noticeable difference. It is made by reputable Indian pharmaceutical companies and is under $1 per 100 mg pill, although importing it isn't legal and so it goes through middlemen, often pretending to be Canadian. Given supply chain problems and mail delays (ours and theirs), you should allow at least a few weeks for it to arrive.

Try 2 weeks of not watching porn and masturbating before seeing your sex encounter with a provider. And maybe adding some exercise and better eating habits can help with performance

Any Man that has an ED problem should first see his doctor and get a prescription for the Blue Pill. Also, If any man is stressed out about anything (That could be the reason).

If not, is there a reason why?  
.
If you're simply too embarrassed to speak to your doctor, there's an easy solution these days.  There are lots of online companies, like ForHims, that will prescribe the pill for you after a 10-minute video chat.  They are legit, US-based companies, so you're not doing anything illegal or gambling by sending your money to an overseas company.  They use the generic version of viagra and cialis, so their pills are relatively cheap.  
.
You can also customize the number of pills you get -- if you think you'll be having sex four times per month, you can get a subscription for four pills per month...  but if you think you'll be having sex six times per month, then you can get a subscription for six pills per month...  and so on.

You eat, sleep, and exercise well which means you should have no problem getting an erection.

How much porn do you watch???  
If you watch a lot of porn you might have been desensitized unless you see hard core content.

If you have a lot of stress, anxiety, depression, or any other mental imbalance it will effect your sex life cause mental issues release cortisol and cortisol attacks your testesrone which destroys your libido.

I'm late 30s and had issues just like you and advice I got from TER members were exercise especially squats and abs, sleep and lots of sleep, and lower stress. After following their advice I realized everything was working just didn't have things in correct location.

I'm 60. Maybe if I want to be sure of a big load in her mouth I abstain for two full days.
Five years ago it was 36 hours.
The above stats are only in reference to cum volume and exit velocity, not ability to get it up. If you're in your 40s and can't get a woody three days in a row with a hot woman, see a doctor. Internist, urologist, psychiatrist; whatever it takes.

 
Or are you dumpster diving with fuglies?

of weightlifting experience that if I have a bad workout, the solution is not to work out LESS often.  This approach to sex  sounds unbelievably counter-intuitive to me.  Since I'm single and will be 64 soon, I don't always have access to a real-life girlfriend, so one of the benefits of P4P participation is that I don't have to resort to jerking off if I'm horny.  I generally schedule 3 sessions a week, and that seems to be the right amount at my age.  However, if I wake up in the morning and feel the pressure to release building, I simply book an extra session for that afternoon.  Trying to decide whether to rub one out or not once you are over 20 seems a little obsessive.  Just listen to your body.  If you're horny, book a session, if not, let it ride a day or two or until your next regular session day.  Not training your body to produce semen on a regular basis seems the same to me as not training my muscles to be ready to lift a large weight the next time I need to.  it's a slippery slope that only points downward.