I don't think I've ever even rejected
but I have been broken up with cause my poly dude found another girl he liked more who wanted to be mono, and another time cause my poly dude wanted to be mono himself
don't usually gotta wait lol
but I do tend to do a lot of asking out and so far nobody has said no iirc, tho maybe this happened once or twice before cause they already had a monog partner and I forgot about it?