Being in love or not

How do you really know if your husband/wife is (or was) in love with you, when they act on impulse much of the time? This is very hard to understand because of the drastic change from dating to marriage, with almost a complete turnaround in actions. It IS hard to believe that they still love you when there is no more affection, and you end up living as roommates. I'd like to hear some view points from those who have ADHD, as well as others. THANKS