Even if we disregard all the lofty feelings, there remains sex, which is fundamentally necessary for an adult.
What does ejaculation have to do with it? Yes, I know that pleasure can be derived without a partner. Perhaps homeless people, foresters, and other sociophobes do just that.
But if, in your opinion, ejaculation is the only reason for needing a partner, then I have bad news for you.
Also, Ghost, you still haven't answered why mercenaries are bad. Do you have no answer?