What is the ruling on becoming infatuated with a non-Muslim actress and becoming attached to her to the point of wishing to marry her, given the inability to stop feeling this way? And what are the consequences of continuing in this?

One must lower their gaze from forbidden things, for looking at foreign women with lust is forbidden and invites infatuation. The adultery of the eyes is looking. Whoever falls into this trial must remember the flaws of women. Persisting in forbidden looking is an insistence on disobedience, and some scholars may consider it a major sin if it is with lust and fear of temptation. It is recommended to read my two books: "Dhamm al-Hawa" (Censure of Desire) by Ibn al-Jawzi, and "Al-Dā' wa al-Dawā'" (The Disease and the Cure) by Ibn al-Qayyim.