Am I reading too much into the "can you stay here and talk to me" while she was in heat?
I expect there will be drama of sorts that comes out of that talk, but I don't expect it to be drama of the potential love triangle kind. What I expect it will be is that her boss is offering her a promotion or something, perhaps even a partnership in the shop, because she is so talented and doesn't want to lose her and the customers that would leave the shop if she either ventured out on her own or went to another shop, so she wants to try to ensure that Rina is happy working there and doesn't do exactly what she's thinking of doing, which is opening her own shop, even if it would be part-time at home.
Meanwhile, I get the feeling that Rina is actually growing less interested in the idea of working from home than Yuna is because of the stress it would put on Yuna, while Yuna is looking forward to being together with Rina while they both work from home. I doubt that Rina will talk with Yuna about her boss' offer until it's a done deal and make Yuna feel like she's not quite a full partner in their relationship. Hence, drama...