Cuckold Fantasy Night In

Start the scenario with your partner getting ready for a date. You stay at home, as they dress up. They leave the house, leaving you alone. After some time, they return with a 'mystery guest'. From here, you play along as the cuckold, guiding and observing the interaction between your partner and their guest.
You can explore various situations that could unfold - maybe you are tied to a chair and only able to observe, perhaps you are tasked with fulfilling their requests, or maybe you are only allowed to listen from another room. Remember, all actions should be consensual and previously discussed.
Throughout the night, you can switch up the roles, if all participants agree. Ensure safety words are agreed upon in advance to guarantee everyone's comfort.

Discuss the boundaries and safe words with your partner. Introduce the idea of having a 'mystery guest', this could be a mutual friend or just be an imaginary person, depending on your comfort level. Decide on the roles and the extent of the play.
Your partner should dress up as if they are going for a date. The more realistic it seems, the more intensely erotic the experience is likely to get. If possible, set aside a room for the scenario and prepare any props you might need, depending on your selected role.
Make sure your environment is comfortable, cozy and inviting. Lighting can aid in setting the mood, dimmed lights or warm toned fairy lights can enhance the ambience.

Safety and consent are paramount. Ensure all participants know the safe words and respect them. Discuss possibilities, roles, and boundaries beforehand.
Include actions or phrases that might elevate the scenario, like optimum reaction at the climax or certain talk which can turn up the heat.
Despite the scenario, remember it is just role play and the trust between you and your partner should not wane. Moreover, constant communication after the roleplay helps in maintaining the bond stronger and understanding each other's needs and desires better.