I think you are confused about ARP requests. ARP requests are sent from a source host to the broadcast address, and every host on the broadcast domain will inspect the request. Only the host with the IPv4 address in the ARP request will reply. All other hosts on the broadcast domain will ignore the request.
For a layer-2 broadcast domain, a router is just another host, so unless the ARP request is for the router itself, then the router will ignore the ARP request. Because ARP requests are broadcast, they are not routed to any other network.