Why would a man feel no guilt for cheating on me with his ex gf?

He probably does unless the lust got the best of him, I have cheated once and felt bad since and Never did it again I feel Really bad I hurt someone who loves me unconditionally with all their heart so I think he feels bad unless Hes a monster

He does not care about you????

Some people don't have as strong consciences, people can murder others and not feel a hint of remorse.

Probably because he might not love you.