With my lover, my lover said that he liked my best friend's personality. My best friend's sister sent me a message asking him to treat me well. He actually took my sister away.

Not overly sensitive, your lover just has ideas about your best friend.

However, since you are a lover, do you still want to have all his love?

The relationship between lovers is inherently insecure, because no one needs to bear any responsibility to anyone and has no obligation to be loyal to each other.

If you can't accept his playboy, then break up.

Also, what do you want from him when you keep a lover relationship with him?

Freshness? The thrill of cheating? Or material enjoyment? What are you worried about if you have to keep getting these?