If I were him, I would invite her over. I would open the windows and charm them so that the cool breeze from the storm could waft in but the water stays out, and I would turn on some soft music and ask her to dance with me. I would hold her close and tell her a story against her ear. And when she was ready to go home, I would kiss her forehead and send her off with positive thoughts for the future.
Because she reached out. Because she gave me him hope. Because he's willing to be her secret if it's what she needs. Because having her for even just that night in that way would be enough to sustain him, to reassure him that she's worth every stolen moment, every hint of something more, even if it can never truly be.