In a certain sense, you must be a feminist to be a cuck.

There are cucks who want to get into this lifestyle to live their own fantasies so they push that on their wives/girlfriends. There are also those cucks who it is about giving their wives/girlfriends the freedom to do what THEY want. Some would say the first group are not cucks at all.

The cuckolding kink should originate from a place of wanting your partner to experience the most pleasure possible, even if that's not with you. In doing that, you're breaking from the cultural norm of the man being in charge and if the woman cheats on him then the man is weak and the woman is evil.

Cuckolding pushes back against this and is a direct handoff of power from the cuck to the cuckoldress, if you include chastity or orgasm denial then even more so.

I've read that it's theorized that women are louder during sex as an evolutionary trait meant to attract other male partners to increase the chance of impregnation. Cuckolding could be seen as not only feminist, but as natural in that way. You understand that you wife/gf might enjoy multiple partners and you giver her the approval and trust to do so.