Compare it with stealing or killing - sure, it's wrong, but it can still actually be the right thing to do. Peter gives the hooker Rahab credit for lying and misleading some soldiers. And you can probably think of a situation where killing someone would be right, yourself. Like if you had to choose between two of your daughters and an enemy soldier.
So many christians can't handle a world that is in full colour and do their best to reduce it to black and white.

-
we can handle "colour" just fine - just don't twist the bible to say
& teach what it does not to condone lusts & desires as if God's
ok with it.
We aren't in the OT anymore, we're in the age of grace and we have
God's law written on our hearts.
The NT is clear on marriage of 1 man with 1 woman (as Jesus defined
it in Mat. 19) and the instructions for church elders to have
only 1 wife in order to be blameless.
Plus, ALL mention of the married are
singular.
Ephesians 5:33
Nevertheless let each one of you in particular so love
his own wife as himself,
and let the
wife see that she respects her
husband.
- 1 Timothy 3:2
A bishop then must be blameless, the husband of one wife, temperate, sober-minded, of good behavior, hospitable, able to teach;
1 Timothy 3:1-3 (in Context) 1 Timothy 3 (Whole Chapter)
- 1 Timothy 3:12
Let deacons be the husbands of one wife, ruling their children and their own houses well.
1 Timothy 3:11-13 (in Context) 1 Timothy 3 (Whole Chapter)
- 1 Timothy 5:9
Do not let a widow under sixty years old be taken into the number, and not unless she has been the wife of one man,
1 Timothy 5:8-10 (in Context) 1 Timothy 5 (Whole Chapter)
- Titus 1:6
if a man is blameless, the husband of one wife, having faithful children not accused of dissipation or insubordination.
Titus 1:5-7 (in Context) Titus 1 (Whole Chapter)
So obviously there was a stigma of wrongdoing in polygamy in
the NT. & obviously having sex outside marriage IS ADULTERY.
(nevermind fornication exists in marriage also)
& it's not the same as swinging anyways; where there's no
responsibility to random sexual partners - we don't attach SIN to
our faith & flaunt it as good. Period.
It's the abuse of another person for one's sexual pleasure
That isn't "color" it's evil.