He thinks marriage is boring

I am a non adder and my husband is a medicated ADHDer.  I am 35 and he is 41.  We have been married 3 years together for 7. He recently started treating his adhd over the past 8 months or so.  He has been taking several anti-depressants and adderal.  We have always had a happy relationship, we worked out ways to communicate our needs to each other and we have a fantastic sex life.  Last week my husband came home and told me that he just didn't feel the spark anymore, that he loves me but doesn't think we are intellectually compatible.  One day he says one thing and the next he says we have reached a plateau and we can't go any further or our relationship has run it's course.  We are in marriage counseling and I am hoping it will help.  I am looking for advice from ADHA men who have fallen out of love with their spouses.