At the time that was huge and ridiculous.
The suits from network gave Joss these parameters for season 4.
1. You're not allowed to tell the audience that they're gay directly.
2. You're not allowed to use the word Lesbian or girlfriend.
3. You're not allowed to show them making any physical contact.
Which is why Joss had to use metaphor's about "witchcraft" and the Camera always pulled away or willow would look worried rather than answer a direct question.
The "success" of the relationship, no noticeable backlash, meant that by season 5, Joss could say "go fuck yourself" to those rules.