It should be easy to annul a marriage if the couple did not consummate it

No. In a sentence like "He was a consummate gentleman" it means he was a perfect gentleman. As a verb, when saying "We will consummate the deal tomorrow" it has no connotation.

He refused to consummate his arranged marriage on the grounds that he was a homosexual.

(as an adjective) Like all sociopaths, she is a consummate liar and manipulator.

(as a verb) Maybe you should wait until marriage to consummate your relationship .

Consummate.