He speaks angrily of an ex
You think, “That’s a good thing! That means he definitely doesn’t have feelings for her anymore.” Think again. Do you really give much of a damn about exes who you don’t have feelings for anymore? In other words—would you get worked up into an angry, cursing vent session about them? No way. If we don’t care about someone, we don’t get mad about them either. If he talks smack about an ex often, that hate is most likely mingled with love. Also, it’s just immature to bad talk an ex, especially to a new love interest!