I have been using generic Viagra and stimfapping (amp and methamp) for about five years ago. For the fifteen preceding years I would have sex or fap on meth without an ED drug. When I started having issues with erections, I was prescribed Cialis and then Viagra. My doctor said it was probably safer, the vasodilation of the sildenafil counteracting the constriction caused by the speed in my heart. It's the same thing for cocks. I have difficulty with erections when not medicating or abusing stims and use a lot of sildenafil every month (4*50mg).
TBH I have been coming to find that my issues with erections were more psychological and sexual than drug related. Over the last five years I became more and more interested in porn, even to the point of fetishizing it. There was a point where I started having difficulties getting an erection trying to have sober or stimsex with my hot wife. Unless, and this is important, she played to my fetishes and porn fantasies, or was letting my make our own pornography, which ended up being the most exciting pornography in my collection for a long long time. Eventually, I started to desensitize to the excitement of my fetishes, and then porn in general, and now I sometimes just have no interest in porn and thus no interest in fapping. (For personal reasons I haven't been pursuing anything but a 100% solo sex life lol.)
I would bet that since your husband is hot and hard for you oral, but not for intercourse, it isn't a drug side effect but a psychosexual one. My suggestion, talk it over, share some secrets and fantasies, push yourselves a little to trust each other more, and you will have a breakthrough that isn't ED drugs or propanolol.
I have a bottle of propanolol and I will see if it helps me, and report on this thread. It is a fully different method of slowing down the CV system which someone else can explain, I think it is a beta blocker.
What chems are you augmenting your sex with?