Fair enough. In the two examples I referenced in my OP, citing the truth would have been hard for them. Girl #1 would be "I liked you and we connected but I wasn't a fan of your Africanized thunder thighs and butt". Girl #2 would be "I stopped caring and don't feel like it anymore."
Normally when I lose interest, I just say something like "I'm stressed out, tired, and busy" which is what I had said to girl #1 and girl #2 to some effect.
I do agree that it's good to stand by your principles, in this case, honesty. People never seem to consider that going against your values isn't necessarily harmful to others, but yourself.
A few months ago I had a girl come over to my place who I never met. She was a hoe but sweet and agreeable. We fvcked all night, some of the best sex I've ever had, and cuddled and talked and laughed. I saw her as a fun FWB/fling potential that I might even want to go on trips with since we got along well. After she leaves, we text a bit over the week, mostly dirty talk (initiated by her) and I try to make plans to see her again. Suddenly, she goes cold for no reason and ghosts out of nowhere. Almost 3 months later out of the blue she sends "hiii" then "wyd" late at night like nothing happened.
Women will do shvt like this to any man even if you give her a good time. Or worse is when you get a girls # and she stops responding then suddenly asks you out 6 months later as if you were just waiting around for her (reality is they have so many options they probably can't even manage it and men are completely disposible playthings to them so they just place them in the queue).