intrapersonal: adj. existing or occuring within the self or within one's mind

Hyukjae thinks, in a somewhat powerless way, that his intrapersonal intelligence is improving every day.

Yes, he admits that he would make pathetic assumptions every now and then. Who doesn't? Even though he doesn't think it's his own fault that he feels insecure, he realises that it's unfair of him to demand the other be there for him every second of the day.

When he doesn't get an instant reply, he assumes Donghae doesn't want to talk to him.

When Donghae tells him to go to sleep soon, he thinks he wants to get rid of him. 

It's pathetic, really.