Well, mind is, in so much as undeniable...Therefore existent in some way.
My question to you would be, what is "immaterial"?
Though for sure, the big question all boils down to the distinction between something and nothing.
And Yes I too came to the conclusion that the Captain and I were essentially coming from the same place in terms of process and function. Though the Captain was keen to embellish base process and function and label the effects with words such as love...Hence "love" is a hormone named oxytocin...Hmmmm, no it isn't, but I understand where they are coming from...Overthink is undeniably the human condition and that which sets us apart from other primates and other species.
So, sex is for procreation, though over the intervening billions of years of species development, only homo-sapiens has come up with the alternative notions and labels that define hormones as love, or love as hormones, and that recreational sex is more than a derivative of procreational sex.