Where even is that mock me line? Or is it in the brothel as well?
It's when talking to Quil Grootslang. Here's all the dialogue options re: romantic interests, and only Gale's is negative.
Quil Grootslang: Is there someone who you think you might love? Come on, I won�t tell.
�Astarion might be the most perfect being to ever walk the day.�
�Shadowheart is pure grace.�
�I�ll never meet another like Lae�zel, that�s for sure.�
�Wyll is such a gentleman, I imagine he�d make an even better partner.�
�Karlach seems like she has so much love to give, if she found the right person.�
�My mind and loins are captive to thoughts of Halsin.�
�I met the most amazing, bewildering Drow the other day.�
and then we have...
�Mock me as you will, but I have a thing for Gale.�There's just a lot of things like this where it seems like Larian did not care much for Gale at all. Dark Urge has a special, unique interaction to murder him (and only him). He gets mocked so much by NPCs (and apparently the player as well).
Like, I guess it is what it is. But as a fan of Gale as a character it is alienating.