Is that possible? A demon can fall in love with a human? If this happens how this affects the magician’s power?
Yes they can fall in love with humans, not all nonhuman entities have a distaste for humans on an intimate level.
As for how it affects the magician’s abilities, depends on if the magician is putting the work in to commune with the entity and if they are collaborating in energy work.
Its happend to me mote then once
Yes, some demons or other spirits can fall in love with a human, they are very much capable of love. Unfortunately, some humans can also fall in love with their own thoughtforms, get caught up in their own fantasies and spin tales of romance that never happened.
The real deal will help empower you and live up to your potential (provided you do the work and don’t expect this kind of love to be passive adoration, 24/7 flattery and cute fluffy unicorns).
The fantasy thing will lead to stagnation and self-delusion.