I understand how you feel. I have 2 kids. When my oldest left for college 2 years ago, I missed her but still had my youngest at home keeping me busy. Now that he will be soon leaving for college hundreds of miles away and with no more kids at home, I feel a pang of sadness. It is bittersweet. Sweet because I understand it is the natural order of things, to see them grow up, become independent, and move on with their lives. Bitter because it's the end of an era where they no longer depend on you in the same way and your role as a parent and relationship with them has forever changed. Hopefully, if I've done my job as a parent, they will be good people and I will always have them in my life but I will miss the day to day interactions, and yes, even the daily frustrations. As the saying goes, the days are long, the years short. It's a reminder to us that we must try to live in the present and enjoy the time we have with them.