I am a lurker here with GHSV1. I want to set the math straight here.
2 years out after infection with 1.3% shedding, that is ~ 114 hours.
Let us generously say PIV sex 144 times a year (that is a lot IMO). Sexual act lasting 10 minutes on average (I am being generous here, average is 5.5 minutes).
That is 1440 minutes or 24 hours of sex/year.
Now there is 8760 hours in a year. Within that span to match the 24 h with 114 h of shedding is (24/8760)*(114/8760) x 100% ~ 0.0036%/yr. Meaning, assuming the shedding remains the same i.e. 1.3% for 35 years of a relationship, chance of spreading is not more than 0.13%. I have also not accounted for the fact that as people get older, they have less sex.
Now we also have to make an allowance for not all shedding being causative of transmission, i.e. viral titers have to exceed a certain minima for transmission.