-The angel said explicitly she would deem their true nature but because they broke the band of love, it implies they don't have someone they love, hence why they committed "a great sin," by not accepting love
-Pilse jumping in front of the arrow is what the angel is referring to by "of her own free will, the arrow accepted," not that she actually loves her
-Even though Pilse is a tsundere, she's never had a violent reaction to that extent as seen at the the end, the reasoning being she takes her job as medic really seriously, and so thinks that being mocked like that is a desecration to the job
-Note the angel says she's awakened the love "for the world," indicating it's more of an omniphillia and not a love of shy specifically
So, no, this is mind control for fanservice, not an actual plot point