Great piece.
I often try to remind people they're quite capable of loving so many people in their life who aren't their romantic partners, so I'm not sure why it's such a stretch for them to imagine how someone can love more than one person in this respect. It seems to short circuit their brain to think in this manner for some reason.
I've found it to work the same way as you--not watering down the love I already have, but just adding to it. I'm thankful for my partners and grateful for the connections I have formed.