Prediction: hishark/bishark always liked Keitha despite being engaged to the princess (I think this was hinted at before?) and so in taking everything Bishark wanted he got Robin to introduce Keitha's ex to the Widow so he could get his hands on Keitha.
𝐼𝓉’𝓈 𝒿𝓊𝓈𝓉 𝓉𝒽𝒾𝓈 𝓌𝒶𝓎 𝓉𝒽𝒶𝓉 𝐼 𝓁𝑜𝓋𝑒 𝓎𝑜𝓊… 𝓀𝒾𝓁𝓁 𝓎𝑜𝓊…