I can’t say I have the answer, just an opinion. I’m certainly not a Dr. So I can’t comment on any potential medical issues.
You did not say how old your boyfriend is. If he is in his 20’s then it could be an entirely different scenario. If in his 30’s yet another scenario, 40’s etc.
You mentioned that he seems to always prefer masturbation. What guy in his right mind would prefer masturbation when he can have the real thing …..Sex?
I have had guys tell me that is exactly why they prefer it on a ‘conditional’ level.
When they could not get sex they masturbated and did so for so long they became ‘conditioned’ to be able to climax that way and only that way.
So when they did have the opportunity to actually have sex they could not climax except through masturbation.
I had a girl tell me once of an old boyfriend of hers that tried anal sex and loved it so much that was the only way he could climax.
It works both ways as I found out from personal experience. 10-12 years ago I was dating a girl who could simply not climax. I bought her a vibrator. That was the best and worst thing I could have done. I was able to get her to climax with oral once or twice but it was long process to say the least.
She could climax with the vibrator in 7 minutes.
The fact that she could climax with the vibrator proved it was not a physical problem but a mental one.
She now prefers the vibrator and she must first use the vibrator and climax before even trying intercourse.
I would suggest getting a few viagra, preferably the 100 mg and split them in half and take a 50 mg.
I will soon be 45 years old and I don’t ‘need’ them but it sure makes one hell of a difference when I take a 50.
You can get them on the internet or a Dr. Will many times give you a free trail pack of 4 or 5.
You will probably be told the same by others here as well. It will make a difference in erection and how long it will last.
It sounds as though you are at your wits end anyway so it’s worth a try.