I'm sorry to do this Dx. I really miss this story and can't seem to remember I will be very grateful for your help and I'll will delete this as soon as possible.
The story is about severus taking Hermione as his apprentice,at first he was reluctant. But at some point at Slughorn party Severus save Hermione from Cormac Mclaggen and their relationship evolve into more deeper and started their romance. Few days after the party Lavender talk about her relationship and sadden by eat. While she cried she ate some chocolate and asked Hermione to have some but it turned out the chocolate have love potion in it and suddenly when seeing Severus, Hermione tell him how much se love and adore McLaggen. That part is only the first half if I'm not mistaken, I think its about 30 chapters.
I hope this info is enough for you guys to know the story. Thank you so much for your to read this.