The reasons for breakup, especially after many years, are almost always that person(s) lied to the partner or themselves about whatever. Delusion may work but only temporarily, if you don't have the realistic picture about yourself and your partner you are slowly creating the story that's one day inevitably going to dissolve badly. OTOH if you are realistic about yourself and your partner you may not feel "butterflies" at the beginning, but as the time goes by your connection will become only stronger.