...for me is when it keeps happening. When it doesn't stop. When I know I'd break rules on account of them if necessary, and I know that they'd never ask me to do something against my principles. When they can command my stubbornness. If I'd go to the ends of the universe for them. If I know that no matter what stands between, I'd either overcome it or outlast it. When the thought of them is a steady faith that keeps me true to ... well, whatever the hell it keeps me true to. It's when they don't set off my "People" alarm. It's when we touch, instead of feeling an unpleasant jolt as if I've run into an electric fence or feeling like I'm touching something too hot or too cold or touching a pet, I feel like water flowing into water.
It's desire, it's goodwill, it's friendship, it's trust. It's the ability to be trustingly subordinate, willingly partnered, or protectively commanding.
I can't tell if someone else loves me anymore. I know unless I know that they are willing to make better anything they break by accident, I won't consider their suit. Not unless they prove themselves trustworthy with not just my person, but my heart and my mind.
There aren't many people who get that response in me. Most recently, I had six blessed months of limbo. I'm glad to be back, don't get me wrong, but I don't think I'd choose to not have that experience. It makes me far more aware what of this is a choice and what is not a (or not a viable) choice. So much of the trust is not a choice -- I could, perhaps, choose not to trust, but it would go against every instinct I had, and I could not again choose to trust where the trust was not actively earned. The love is not a choice. I love so long as I love, and no longer. What I do about it is a choice. The loyalty is, surprisingly, a choice. The feeling is not, but the actions are, and I willingly choose them.