Review the item:
Sparkling with jewelry conned from ex-boyfriends, Gloria keeps an eye out
for new victims with fat wallets, she still needs a pair of diamond
earrings to complement a necklace that she
coerced Ricardo to buy.
No problem occurs between earrings and to. She still needs a pair of diamond earrings is a main clause. To complement a necklace is an infinitive phrase. An infinitive phrase will begin with an infinitive like to complement.
When an infinitive phrase follows a main clause, you do not need to separate the two parts with punctuation.