Can there be ‘reasonable’ discussions of sexual moral questions? yes
One needs though take good care…avoid near occasions for self or others etc…and in the case of this forum…the there are rules concerning content and language etc (see the forum rules and the consiege desk). Sometimes it goes way too far here…(and one can report such to the moderators)
Can there be such discussions that begin to push or even leap over the standards of modesty and/or chastity? yes
And yes one needs to take care to avoid sin in any such discussion…(and even the entire discussion at times!)
Prudence, modesty, chastity, circumspection, custody of the senses…both external and internal (discipline of the imagination and thoughts), right choice of language etc.