Why didnt you just buy it yourself? And why didnt you just communicate with him you wanted more sex? 

Hes probably feeling self conscious now (knowing the average sizes of dildos) and is worrying about his performance.
Hes probably also worried about you replacing sex completely with the dildo (guys are stupid okay) because of the way you worded it. In the future perhaps purchase the toys for yourself, or ask for the toys in terms of increasing the variety of sexual acts you can do with each other.

Straight up saying, buy me a dildo because you dont fuck me enough and ill stop asking for sex. Doesnt seem too appropriate nor optimistic.