Here's Ann's defense of certain homosexual relationships.
This is my brief, uncomprehensive (but hopefully comprehensible), one-point reply:
Romans 1 cannot be contorted to be arguing only against a certain KIND of homosexuality.
"God gave them up to degrading passions. Their women exchanged natural intercourse for unnatural..." 1:26 NRSV
What is against nature and degrading - and the result of God giving sinners over to judgment - is homo-eroticism itself. The Greek "gar", not translated in the NRSV before the phrase "Their women," is an explanatory gar, describing what the unnatural intercourse is: women with women. Not the natural use/intercourse of women with men, but same-sex erotic desire. The homoios at the beginning of vs 27 functions the same way, explaining what is unnatural: men with men, instead of with women. Paul doesn't discuss fidelity to one person; this isn't on his radar at all - the unnaturalness is the homoeroticism.
The passions aren't degrading because they are overly lustful or non-monogamous, but because they are same-sex.
The Bible certainly is not silent regarding homosexual, monogamous relationships.