If this is 12 weeks post possible exposure then you can have every confidence in the negative result.
This is what it said about the test on the site:
The Herpes Simplex IgG test is performed using an ELISA (Enzyme Linked Immunosorbent Assay) test kit manufactured by Euroimmun Diagnostics (Germany). This ELISA test provides a quantitative in vitro assay for human antibodies of the IgG class against HSV 1/2 (group specific) viruses in serum or plasma.
Note: This test does not differentiate between HSV Type 1 and HSV Type 2 IgG antibodies