Your first love isn't always the first person you kiss, or first person you date. Your first love is the person you always compare everyone to. The person that you will never truly get over, even when you've convinced yourself you've moved on.
I feel this way often! Missing someone isn't about how long it has been since you've seen them or the amount of time since you've talked. It's about that very moment when you're doing something and wishing they were right there with you.