We already know about the B&R regulations if you play through Nora's route you find out about it, Bella didn't lie, but she didn't tell the whole truth either...
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So, technically they could legally date even with her being his teacher, but they would have to disclose it to everybody, it seems Bella isn't ready for that so she prefers to hide it...
Yes, and in EP10 she elaborates it further
She's legally married, but the dude has been gone for so long that even she doesn't really acknowledges it anymore, she did in the beginning of the game, but I guess all those near meltdowns we've seen from her in earlier episodes was her coming to terms with this.