I’m thinking that it may have had to do with interal struggle.
A) Cora told Regina that she made deals to get them out of poverty, so maybe Regina thought that if she went back to poverty, the deals that cost herself or her family were made for nothing.
B) She felt obligated to keep up the ruse in front of Snow White. Regina told Snow that she was going to marry her father because she didn’t love Daniel. If Regina didn’t keep up her end, then Snow might ask what really happend reguarding Daniel. If the truth was known, Cora and her heart reputation would come out to the King, and perhaps many others.