Xeni by Rebekah Weatherspoon
One Kiss with a Rock Star by Amber Lin and Shari Slade
False Notes and Broken Frets by Elle Bennett
Sweethand by N.G. Peltier
Dare to Live, Dare to Love by Nicki C. Moon
Bonus: These are all adult, but in YA, try I’ll Be the One by Lyla Lee. Also, while not a Romance by genre definition, Verona Comics by Jennifer Dugan has a central m/f pairing and both are bi/pan
Double Bonus: While the (male) MC of The Girl Next Door by Amy Jo Cousins does not ID as bi (though the female love interest does), it would be safe to call him “heteroflexible”
