Can someone explain hyperfocus?

So on this forum I have heard the term, "hyperfocus" regarding how romantic adhd partners can be at the start of a relationship. Does this mean that their romantic acts are not fueled by actual love but by there Adhd? Or are they in love when they are romantic but their adhd just makes them show it more? What makes this different than your typical relationship "honeymoon" stage and "comfortable" stage. Every relationship has a honeymoon stage at first and then people get comfortable. How is hyperfocus different than that and how different is it from other relationships when it goes away? 

This is just my personal

This is just my personal experience, but to me hyperfocusing goes way beyond the normal honeymoon phase affection.  When I hyperfocus on anything there is nothing that can draw me away from it.  I tend to devote all of my energy to it and let everything else fall to the wayside.  You're asking if it is sincere and it truly can be.  For me, in relationships, the affection I have towards this person compounded with the novelty of the experiences I'm having can result in this emotional high.  The novelty does go away, however.  Things begin to settle and I fall back into my old patterns.  The sudden change from hyperfocus to normality can make it seem like the ADD partner is being neglectful, but if the feelings were there they do remain there.  As long as there is still room for some spontaneity and discovering new things together, you can keep that spark alive.

Hope this helps.