I'm leaning towards agreeing with
@SomeGuy It looks like he's wearing a prosthetic cock. I'm honestly puzzled by this recent trend of mainstream shows wanting to show erect male full-frontal nudity, albeit with a fake stunt cock. Cases in point; Betty Gilpin's sex scenes in Three Women and Natalie Portman in May December, both instances of which have their co-stars wear stunt cocks.
Wtaf? You might as well just avoid full-frontal nudity altogether if you're not going to actually show genitalia. Some may argue, "oh, it is so that nudity is equally both from the actor and actress". Yeah well I'm still not seeing any full-frontal female nudity from those same scenes. And by the way, I wouldn't care for fake pussy (if that's even actually a thing) anyway.
Ugh. Sex scene making these days have truly lost their artistic touch.