From Ace Part 14

Tails is extremely annoyed and irritated by the fact Sonic and Amy have so many kids. It's not that he is against it, he's actually worried about them rushing into their life so quickly. He desperately tries to talk to Sonic about it, but his embarrasment pushes him away from ever listening. He loses control of this annoyance in the Ace comic when overhearing about Amy being pregnant again, and grows angry and slaps Sonic several times.