I think it is possible that this reflects a new infection but not very likely. The odds of getting HSV 2 at a single encounter that was somewhat protected are very low.
There are no symptoms of seroconversion itself – only symptoms of herpes which are usually sores in the genital area.
I’m sorry he won’t be tested – I think that is really awful and if I were you in this challenging situation, I would be tempted to tell him that you test positive and are considering legal action so if he wants to avoid this, he should document a negative test. It’s extreme, I know but what reasonable person would deny someone this information?
I would retest at 4 weeks ago and see what direction, if any, the IgG is going.