<human>: Recently my boyfriend's (Marcus) behaviour has changed when I mention my best friend (Jamie). He makes nervous jokes when I tell him something Jamie has sent me or talked about online; he has also talked to me about how Jamie is when were on a night out and sounds almost jealous.

Marcus has a female best friend so there's no distrust between us, maybe it's Jamie he doesn't trust? 

I don't believe Jamie has feelings for me so I'm not sure were Marcus' behaviour has come from. Marcus and I have touched on the topic before but he avoids it.

Can you provide a brief overview of the text?
<bot>: How do I reassure my boyfriend he's got nothing to worry about, that no other man is going to steal me away?