It is also worth noting that if you are aggressive towards the nymph, she will respond in kind. So basically, uh, the more often you stab her to death the less often she'll attempt things (and will note things like 'Ugh, you, you're no fun').
Otherwise, Nymphs in particular are 'literally magic' more than anything else, and the curse of lust is clearly effecting the herbalist just like it is to everyone else around. Any revulsion you feel is similar to how I presume most NPCs feel when you use a love potion or lust potions on them if they weren't otherwise interested, haha.