I'd like to hear how you would personally describe it, and how you can distinguish it from more transient things, such as mere loneliness, or lust.
Personally, I would say when one experiences the true emotion, they feel as if they are briefly in a transcendent state of mind, at one with all of nature, completely in the present and devoid of distracting thoughts; an emotion otherwise only accessible through meditation and connection to a higher power.
Spinning the orthodox understanding of Christ's Great Commandment as "atheistic" is unique. Never heard that before.
Either way, it's certainly not "out of context". There is no additional context. That's the whole parable. If Christ needed to mention the Samaritan's feelings to clarify His explanation of how to love your neighbor ... I trust He would've.
I think it is a blend. That settles toward this.
Emotions including friendship, lust, etc start the foundations. It builds as it moves more toward a deep friendship. Sex can deepen the bonds if it is focused as a shared mutual pleasure.
Yet so can mutually shared experiences also form strong bonds. You see such acts (a decision to put someone else's interests before your own) in war as much as marriage, I would guess.
Marriage for me is work. My wife and I both agree marriage is work. It is good work and has it's pleasures and joys. but I do think over time a good marriage is a balance of "a decision to put someone else's interests before your own" and good communication so that everyone has their needs and interests taken care of.
"That reply was all over the place."
It is not alone!
A consistently higher concentration of oxytocin, relative to serotonin.
Oh, stop it, you're getting me hot.
That would be the serotonin + dopamine, mostly.