slow response

​i have been in a relationship with a man with adhd for 8 months.  i have had a few trying moments but i feel that i really love him and am accepting.  my question is that when he travels for work it sometimes feels like he forgets about me and i don't hear from him for a few days.  in this day of technology it seems so easy to just contact me.  is it normal for someone with adhd to just get so busy and stuck in their own head that they just won't contact their partners for a few days??

looking for insight