I've come across the below sentence:
Este año he decidido serme fiel a mi misma y no mentirme
I checked the dictionary and couldn't find the word "serme". What does it mean?
serme = ser + me and means "to be" in its infinitive reflexive form. "Mentirme" is of the same form, mentir + me.
You can add the reflexive pronouns to the end of infinitives, gerunds and affirmative imperative verbs.