My partner has told me he wants to explore cuckolding and I don't know how to feel about it. Part of me is intrigued and part of me is just hurt. Is this a normal reaction?

Cuckolding is a specific dynamic where one partner (typically male-identified in the traditional framing) derives erotic satisfaction from their partner having sex with another person while they observe, hear about it, or are otherwise involved in the experience. The psychological appeal for the person in the cuckold role is typically bound up in submission, compersion, and the specific psychological charge of that scenario.

The hurt reaction often comes from a specific interpretation: if he wants this, he must not find me enough, or he must find others more attractive. That interpretation is usually inaccurate. The cuckolding desire is about the dynamic itself, not about a deficit in the existing relationship. Many people with this interest are deeply in love with their partners and are not seeking an escape from them.

The intrigue you are also feeling is worth paying attention to rather than dismissing. Some people who have this mixed reaction, when they understand the dynamic better and talk through it honestly with their partner, find that the curiosity grows as the hurt decreases.

The first practical step is to ask your partner to explain what specifically appeals to him about this, in as much detail as he is comfortable giving. Understanding the psychological mechanism, what the experience represents for him and what role he imagines you in, usually produces a much more specific picture than 'cuckolding' as a label.

You are not obligated to participate. This is a desire he has shared, not a request you owe an answer to immediately.