That's right.
Takumi thought it was a real date and enjoyed it but then Sakuragawa asked him if they were going back to the shop , how it was called, about paying ... Which implied that he thought Takumi was just working as always. So Takumi got hurt since he understood that Sakuragawa invited him as a host not "the real him", that it wasn't special...
aaaaah ok, now I get it!! Ah poor him :(
And he also didn't deserve that slap -.- but well... it's merely a story after all.
Yeah he didn't deserve it at all I agree. When I read it the first time I was like "what ??? why ?" and got angry but well like you said it's merely a story ヾ(❀╹◡╹)ﾉ~
http://www.mangago.me/read-manga/kibun_wa_joujou/mf/v01/c003/22/
I don't completely understand what's going on. I mean I know what his problem is, but not what Sakuragawa said to make it come to that... did he think it's work for him or...?