Kim didn't steal Puff, she was all in Misa's ear telling her she shouldn't be with Puff cause he was a dog etc.
When Misa dropped him, Kim happly picked him up
No she stole him. (well I really don't believe that anyone can steal a man from you but that's besides the point)
However, Kim's bum ass got kicked to the curb by yet another Uptown affliated artist she was messing with...was out of a place to live and Misa took her in to live with her, Puff and Justin with Quincy, because she had no place to go.
And Kim repaid that charity by starting an affair with Puff. Prior to that Kim and Misa were very, very good friends. That's why Kim gets no sympathy from noone in the industry.