I use to have this really bad too. I figured this was for two reasons. Number 1: weakened pelvic floor muscles. Before I crashed, I could perform strong kegels and hold them for long periods. After I crashed, I could barely do one, and i would feel discomfort every time I’d try.
Second reason I thought was because I was so nervous and anxious about maintaining my erection, that I would psyche myself into cumming quicker so I didn’t lose my erection. It became a vicious cycle/mental issue for me, becAuse anytime I would lose my erection before ejaculation, I would get severely depressed afterwards. So my body got use to ejaculating quickly and it became the norm for years.
I’ve been having better luck with erections as of late, and I’m finding that the harder my erection gets, the longer I can last generally. So erectile dysfunction and PE seem to correlate with eachother, at least in my experience. I recently had shockwave therapy to my perineum, so I’m wondering if maybe that is having a positive affect on my pelvic floor and helping me last longer.