Complex sentence: Ben (Adam Scott) initially turns down an invite because he doesn't want to get too attached to everyone since his job will have him move soon, but relents when Tom invites him again at Leslie's urging.
Split into simpler sentences: Ben (Adam Scott) initially turns down the invitation because he does not want to get too attached to anybody, since his job will require him move soon. However, Ben relents when Tom invites him again at Leslie's urging.