When I do incremental etl from rdb to gdb, how to find relationships should be cut off

hi I'm doing etl from rdb to gdb(graph db).
It was no problem durinng intial loading.
But I had a question when I just do incremental etl from rdb to gdb.

there are sample data below:
RDB
col1 col2 audit_col
node1, node2 2023-11-15
node1, node3 2023-11-15
GDB
node1 -> node2, node1 ->node3

it was changed on RDB below:
col1 col2
node1, node4 2023-12-01
node1, node3 2023-11-15

I noticed changing data row:
node1, node2 2023-11-15 => node1, node4 2023-12-01

So, I can create new node4 and create new relationship between node1 and node4.
But I don't know the relationship that was cut off between node1and node2.

For I acknowedge that, I should create rdb snapshot table that keep previous status and compare both table.
or I search all relationships of node1 and node4 in gdb and rdb, and compare both data.

is there the best way to find relationships to be cut off?

help me please.