Reform/Progressive Traditions on 17th of Tamuz

Hey, guys!

For the context: I was raised conservative, now I am going (and enjoying!) to a Reform space. But sometimes I get a bit lost.

The conservative shil I went was used to keep the fast of 17th of Tamuz and, also, people are not allowed to marry at the Three Weeks.

This Saturday night 17th of Tamuz begins and I was just invited to a jewish marriage in our shil that will happen… the Saturday night which 17th of Tamuz begins! So I am a bit confused here. What are the thoughts of the Reformist Movement about this minor holiday? How do you celebrate in your reform shil?

Thanks for the help! So glad to share this here and learn with you guys!