Soft is many things. It's a feeling, and an adjective.
What is Soft as a feeling? It's like love, but the kind of love that makes you simply... soft. You want to stay up with your someone, you want to simply cherish them. You feel bubbly and happy and safe. You feel Soft.
As an adjective? Well, Soft is also a texture, but people can be soft. If someone is soft, they make you safe. You light up when you see their notification, their avatar excites you. They are never mean, and you trust them.
Person 1: God, I'm so soft for (person)
Person 2: oh?
Person 1: You're so soft~
Person 2: oh shit ok <3