The First Series I Loved:
The Sunfire Romance Series put out by Scholastic.
Here's what Wikipedia had to say about them.
The Sunfire books contained two themes: history and romance. Each book featured a teenage girl who experienced a particular period or event in American history. At the same time, with very few exceptions, the girl was torn between two potential lovers.
The girl was typically ahead of her time in ideas and actions and the suitor she almost always chose was the one who approved of or accepted her actions. The cover art always featured the main character flanked by her two potential lovers, along with scenes from the historical event or period that was the setting for the book.
The books were written by a group of authors, Vivian Schurfranz (9), Jane Claypool Miner (6), Candice F. Ransom (6), Mary Francis Shura (6), Jeffie Ross Gordon (2), and Willo Davis Roberts (3).
Let me share of picture of my favorite three titles so you have a visual. Seeing the covers might also jog some memories out there.