Riviera Maya and the Yucatan are generally popular tourist destinations, thus they are generally safe for solo female travelers. However, like any other place in the world, there can be isolated instances of street harassment. It's best to remain vigilant, respect local customs and be aware of your surroundings. The prevalence of this behavior is relatively low compared to other destinations. Stick to well-traveled areas, especially at night, and you should largely avoid overly negative encounters.