To cuck or not to cuck

My young fiancee and I have been together for a few years. We are both Chinese Americans. She is petite around 5 feet and has angelic face, gorgeous body, long silky hair, sexy legs, and babyish feet. Friends think she looks like twin to a famous Chinese idol actress. I am lucky to be her first and only man so far. She had never dated before we met and I popped her cherry three months later while she was still in college. Outside she is beautiful, charming, intelligent and conveys an aura of elegance and gentility. But only I know how amazing she is in bed. Her handjob is incredible with her warm soft sweaty palms, so is her blowjob with her little mouth and playful tongue. Moreover, she has a very tight pussy, as tight as she was a virgin, and gift to control her vagina muscle to massage my cock skillfully. We have had active intensive sex, but her lust for sex keeps growing. Due to our age difference, It is getting hard for me to satisfy her especially during her safe period that she would ask me to creampie inside her pussy once or twice a day. Last Xmas, we started to discuss about cuckold lifestyle, but we are slow and reluctant to talk about it more because of our conservative background until it almost happened a month later. Alan, my best white friend ever, came to visit me and stayed in our place over a weekend. We talked hours and hours since we haven’t seen each other for years. He is handsome, considerate, thoughtful and loves asian girls. He had been single for a while since his last asian ex-girlfriend. Though they met before, he didn’t see her in the first night because she is shy by nature and usually hides in bedroom to avoid seeing guests she doesn’t know well. Next day, Alan went to see his ex and then we picked him up to have Korean dinner. She was still shy but seemed to warm up after he made a few jokes. On the way home, she told me in Chinese “He is still very handsome and attractive”. While waiting for her to shop in bakery, Alan told me that he still felt sad about losing his ex. Being sympathetic and wanting to make him happy and less lonely, the idea of letting him sl**p with her came crossed my mind. Back home, she very unusually prepared desert for him so I could tell she also liked him. After saying goodnight to Alan, she started to handjob me. Then I joked to her that letting Alan join us in bed. Instead of protest I had expected from her, she surprised me by saying “He would not be interested in me since I am not attractive now”. With my cock instantly hard on, I lied to her “No! He just told me today that you are very hot and he envies me”. She immediately blushed so much, became very horny, and jumped to blowjob me hard like it were Alan’s cock to hide her embarrassment. Since it was the last day of her period, I quickly unloaded my cum inside her mouth given her extremely affectionate handjob and blowjob. I fell into sl**p soon and waked up a few times with dreams that she was blowing Alan in shower and she was riding crazily on top of him in our sofabed then realized she was sl**ping sweetly besides me. Giving Alan a ride to airport, I was thinking to ask him to change flight and stay a few more nights, then most likely it would happen that he could have unloaded years of cum inside her tight pussy which was exclusively mine, and I would love to make him and her very happy. But I was too timid to ask him. I tried to convince him to move here, so we could hang out more and share the rent without mentioning the thought of sharing her sexually together. Since then, she and I have been fantasizing her sex with Alan. I asked her about threesome, but she said “No threesome! I will be nervous if you are here. But I don’t mind having sex with him alone and tape video for you to watch later if he doesn’t mind”. We started to have dirty talks during sex like “What do you want to wear for him? I would wear your valentine gift pink Victoria’s Secret lingerie and watch him pound me doggystyle from mirror” “Do you want him to wear condom? No! I want him creampie inside me” “I want his cock to stretch your pussy and make it loose”. She became very slutty and her thigh was always soaked with her juice which rarely happened before. However, I may finally happen. Alan never knows our fantasy. But her fantasy started to make her confused about sex and love that she missed him though they never dated. Last week she got a news that she will have a business trip to Alan’s current city soon and she will stay in a downtown hotel very close to where Alan lives. Knowing the fantasy may become reality, she got cold feet that she was worried that Alan may not even like her, so I guaranteed that he for sure would love to do her with or without my blessing. Personally I love her and want her to be happy and wish Alan would enjoy her and even move in with us to help me satisfy her growing need for sex. When she and I get married, he will be our bestman and get her wedding garter from her thigh, then we will have threesome together in her wedding night. But to make this happen, I need courage to tell him this taboo and suggest him to date her in a fancy romantic French restaurant and she will be his that night and ours together. I know she would love like to have him as a secret life-long lover with my blessing. But I don’t want to risk my long-term friendship with Alan. What should I do?