I still head canon both Will Graham and Sam Winchester to be asexual.
Sam has had sexual activity and liked it, he's still quite awkward around women (excluding his soulless yearly episode) and when Dean consulted him in asking Sarah out, his first response was "no, Dean! I'm not going to..marry her or something." Which Dean laughed at. Obviously Sam sees sex as something to be had in a committed relationship although up to date, Dean has changed his perspective on that. Sam still doesn't like to dwell on the sex topic. That's why I headcanoned him mostly asexual, and only falls for women with what has be provided by the show.
Will Graham I used to view as aromantic, seeing how his unstable episodes he /knew/ wouldn't be able to work in a romantic relationship. But he does long to be with Alan Bloom, and I believe Alana does the same, so it cancels out the idea of Will being aromantic. But asexual? Yes. Never have I seen Will have sex, or inclined he even wants it. As a man who deals with hallucinations, post dramatic stress and 99 problems with 89 being FBI cases, he really doesn't view sex as a necessity.
