It appears to me that the boyfriend agreed to help her contact a potential murderer for her husband, but the boyfriend was not, himself, the “hitman,” that is, FBI employee, and the woman set up the attack on the boyfriend’s daughter without the boyfriend’s knowledge.
It’s weird that she could get 10 years for trying to buy two murders but 20 years for destroying evidence.
Isaiah! Who you gonna believe, me or ya lyin’ eahs!!
Destroying evidence is a crime against the government while the two attempted murders are merely crimes against individuals. Your death is only half as important as making some civil "servant's" job a little more difficult.