Romance writers deal often with mood, and changes in mood. Our heroines can change their minds quickly, as they are presented with new information or they reassess.
William Zinsser, in his On Writing Well, offers a myth buster. He says, "Many of us were taught that no sentence should begin with "but." If that's what you learned, unlearn it--there's no stronger word at the start of a sentence. It announces a total contrast with what has gone before, and primes the reader for the change."
"However" is best used mid sentence, as in "It is, however, a weaker word."
"Yet" does almost the same job as "but," though its meaning is closer to "nevertheless.: Either of these words can replace a whole long phrase that summarizes what the reader has just been told. "Instead," "still," "thus," "therefore,."
Using "meanwhile," "now," "later," "today," and "subsequently" ensures the reader follows a transition in the story.
And she'll thank you for using only one word.