The scene starts when you talk with Lind in the meeting room on the right side of the sleeping chambers in the castle of Aldlyn. It requires her previous CG scenes, and that the marriage system is unlocked to the point where you can pick a wife.
I'm not aware of an actual bug in her event. Most of the time people are just missing a requirement for the next step of the events. https://renryuu.miraheze.org/wiki/Lind If you have a problem despite having all requirement, you can send me your save file per mail to Naughty-Netherpunch@web.de and I'll check if something is wrong in your save.
During the events with Lind, you visit her house in Aldlyn at the end of a date, which gives you a message like "You can now visit Lind at her house!" which is where you have to go for the next step of her events. In her house, there are a few sparkling objects, which you have to interact with to advance the events to the next step.
