David Robinson in his book Herbert Armstrong's Tangled Web states that HWA appears to have had two romantic relationships in the period between his two marriages (1967-77). If there were others Robinson did not hear of them.
Herbert Armstrong has been "in love" a number of times during the past decade. He said himself he had been "in love" with "Amy" when she was 25 years old. He reported this to a group in Big Sandy. he did say, when it was over, that he thought it might have been infatuation.Robinson also notes how HWA told him in great detail how he lost his virginity to a prostitute in New Orleans.
But earlier there had been the young Filipino girl whom he had brought over to this country, according to widespread reports. However, he never did bring her to church with him! He apparently kept her under wraps. (Chapter 7, p. 88.)
I had not heard about these romantic relationships HWA had before reading this book.
You can access Herbert Armstrong's Tangled Web from Exit and Support Network. Just email them and request it.