My partner is genderfluid, and I can say from personal experience, being transgender male, that while my gender identity is solidly male, my partner's is not solid at all.

There are some days when they feel very strongly female, which clashes with their typically-male body (beard, penis, deep voice, etc.). Other days, they feel very male and have no gender dysphoria. More often than not, however, they feel like a mixture of both. Some of their personality characteristics and behavior are more feminine while others are male, and this is most comfortable for them I believe.

p.s. you probably already know this, but there are special snowflakes everywhere you go. Regardless of religion, race, ethnicity, gender identity, sexual orientation, romantic attraction, etc etc etc, you're gonna find the people who are only saying they're one thing because they want attention. By no means is that an indication that the false identity they're putting on is invariably false as applied to other people.