Berothed/Engage

I'm not a native speaker, so frequently I don't know underlying semantic subtleties of synonyms; what connotations they bear, which may be antiquated or very official, which are specific to given region or group and such.

Currently, I'm struggling with:

• engagement / betrothal,

• betrothed / affianced / engaged / to be married

• betrothed / a wife-to-be / husband-to-be / fiancée / fiancé