As of a few months ago, I suddenly became scared of getting on trains, with the fear that theyll crash (resulting in me trying to avoid then, taking bus when i can and having frequent nightmares of train crashes) and another is of an explosion or meteor striking, any noise of an airplane causing my body temperature to rise and i get really scared, also causing nightmares.  

Ive tried to think back and the only possible explanations I can imagine was that my ex had both a severe fear of trains and meteors striking, but id never had these fears before and i dont understand why they would begin at our breakup, or how i could "learn" them in that way