The feeling you get right after being separated from the person you love, such as through saying goodbye after spending the day or
night together, especially when it was particularly romantic throughout, or at the end before leaving. You start to
miss them horribly even though you were just together, and you can't think of anything but them, or focus on anything else but the
time you spent together. Zoning out, feeling like there's a knot in your chest, being anxious, and generally being really happy and/or sad about both the
time spent together and your not being with eachother like you were earlier are common symptoms.
To compare, it's like literal drinking. After sixteen beers (or kissing, snuggling, sex, or otherwise
romance in general) you can't simply stop drinking and decide you're no longer
drunk, you will still feel the affects of said drinking (or again, in this
case, kissing, snuggling, etc.) and must slowly wind down from the earlier events.