It is hard! I'm with DH on this one.
Tact is lovely and appreciated but I prefer to know the truth, particularly if I am the one being dumped.
I finally had a deeper conversation about why he ended our sexual relationship with SW. (Yeah, I'm talking to him again. It's been good and I am really glad I took the space and distance.) He had told me that he was ultimately monogamous and knew I was not monogamous. This time around, he also said that the chemistry between us had faded. So while it is not fun to know this, on the other hand, I know NRE fades and sometimes so does the relationship. So I am much more at ease. I knew that the non-monogamy thing was not the only reason and now that he has filled in some of the blanks, honestly I feel better and find it easier to be platonic friends.