I’d like to recommend three shows that have incestuous themes and relationships:
Águila Roja (Red Eagle): Brother/Sister and Aunt/Nephew.
[Ending Spoilers] Irene kills herself soon after she finds out that she’s been sleeping with her blood brother, Hernan. Her nephew, Hernan’s son Nuño, who she was in love and had an affair with, never finds out about their blood relationship. Hernan and Nuño survive.
Nissaga de poder (Lineage of power): Brother/Sister.
[Ending Spoilers] It ends in suicide as well, but at least both characters, Eulalia and Mateu, die together and in love. They also had a son together, Eduard. It’s the relatively most positive portrayal of consanguinamory out of these.
Lo que escondian sus ojos (What her eyes were hiding): Half-Brother/Sister. Based on a true story, real-life incest.
[Ending Spoilers] Yet another suicide after the reveal of their blood relationship. This time only attempted however, because the brother, Rolo, talks his sister Carmen down from jumping off a cliff. Carmen locks herself into a convent for the following years. This happened in real life too.