But, is sexual relations outside marriage sanctioned by the Bible? (I’m talking more about pre-marital sex or among divorcee, not cheating, which is still considered bad.) Or we simply look the other way now?
No and no.
An emphatic NO!
"God ordained marriage as his only authorized means of sexual cohabitation." -- Adultery (Ian McPherson). The entire article from this congregation of the church of Christ is worthwhile reading and, in my opinion, it's sound doctrine.
I think the Bible doesn’t make it mandatory to have a ceremony to recognize a union, but it recognizes that the only way that one can honour marriage is to be committed to a person of the opposite gender permanently, without straying.
Anything less is a strike at the foundation of it.