Is the premarital sex permissible in a betrothal in a Catholic perspective?

[metis]

Oh, because this is a Catholic DIR, I will refrain from making any additional comments here.

 

[URAVIP2ME]

Secondly, fornication is not the same as adultery, the latter of which is considered to be a very serious sin. In the case of the former, the question begs who is being harmed?
Finally, there's a statement acceptable within the Church of "Let your informed conscience be your guide", namely that it is the couple that has to make the ultimate decision on this because they're the ones that have to deal with the consequences.

I agree fornication is Not the same as adultery.
Jesus did Not use the word adultery at Matthew 5:32 nor at Matthew 19:9.
The reason Jesus used the word fornication is because the word fornication ( from the Greek porneia ) is more comprehensive in meaning. For example: Fornication could include even having sex with an animal as unscriptural.

As far as Jimminy Cricket's 'let your conscience be your guide', who'd want the conscience of a serial killer.
An informed ( or scripturally trained conscience ) could only be guided that fornication is scripturally wrong according to
- 1 Corinthians 5:11-13