Would this be unethical?

[Simon Ghandil]

When an experienced wholesaler helps an amateur wholesaler by providing a cash buyer for a 50/50 split, then when the amateur gets his second deal, he contacts the cash buyer and sells him another house, cutting out the person who introduced him to the buyer.

Just something random I thought of tonight, and wanted to know; if this happened to you as the veteran, would you be angry? If you were on your second deal and had that option, what would you do?