My boyfriend wants a threesome, but I don’t

I didn’t mind indulging my boyfriend’s fantasies at first because they were not extreme and they were something we kept between the two of us

Now, he has asked if we can have a threesome with another woman. I don’t want to do it but I don’t want him to think I am a prude. I am also worried that if I refuse, he will do it without me.

No offence, but you really are going out with a dope. Threesomes are an extremely intimidating concept and the idea needs to be broached with the utmost sensitivity and consideration. You have indulged all your boyfriend’s fantasies to date and he should be deeply grateful.