Guys, is it possible for guys to lose interests in someone in a day?

Hi there!
I recently had my second date with a guy from my uni. We first got to know each other through instagram since he wrote me first few months ago. After the first date, we got even more intimate, wrote almost everyday flirting each other, sending selfies, sharing our daily life... etc. After a month since we both were quite busy with our life, we finally had our second date last week at my place.
We drank quite a lot, especially I was a bit drunk in the end, and he also seemed quite tired after long day of work. So he went home, hugging me tight in the end. He also seemed definitely interested in me during the whole time. He laughed a lot (so did I), stared at me time to time.. you know positive signals.
Problem here is, he doesn't write me as often as before since then.
Day after I asked him if he got home safely, he answered yes and that he's super tired.
Another day after he writes me he's having a birthday party of his little brother, and that he's tired again. And then two days of silence, I asked him if he's busy again (he owns a startup company which sounds super busy), and he says "Don't ask me, totally exhausted" (kinda sounds like he doesn't want to hear from me anymore... right?) So I wrote back, "oh well... thought something's going on with you." and he replies "na, just way too much to do'"
And until now I haven't heard a single word from him. That was on Tuesday. But he frequently checks instagrams at night (im not cyberstalking him but i just can see that he likes my post and watches my stories etc!!!)
I just can't understand why he's not writing me anymore.. and I miss talking to him.. But I am afraid that I might look to clingy or that he might not want to talk to me anymore.
What so you guys think? Do you think I should move on, since he just lost interest on me? That would be heartbreaking tho... :( But please share me your honest opinions!
Guys, is it possible for guys to lose interests in someone in a day?
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