Yes, it is possible, but it will require calling in to the airline so they can split the booking: basically, they'll create a new booking for him and leave you in the old one.

Beware that this may get charged as a new ticket, so the cost of doing this may be considerable. It's quite possible that it will be cheaper to just buy a new ticket from Malaga to Frankfurt on a low-cost carrier. The good news is that you will still be able to board your flight to Berlin even he doesn't show up.

Alternatively, he can fly with you to Berlin and book a separate connecting flight or train, but this can be risky since the connection will not get guaranteed.

Yes, it is possible, but it will require calling in to the airline so they can split the booking: basically, they'll create a new booking for him and leave you in the old one.

Beware that your partner will likely get charged change fees plus the price difference to flying to FRA, so the cost of doing this may be considerable. It's quite possible that it will be cheaper to just buy a new ticket from Malaga to Frankfurt on a low-cost carrier. The good news is that you will still be able to board your flight to Berlin even he doesn't show up.

Alternatively, he can fly with you to Berlin and book a separate connecting flight or train, but this can be risky since the connection will not get guaranteed.