Under the Divorce Act (Canada), marriage breakdown is the only admissible ground for divorce. Breakdown of the marriage can be established by separation, adultery or cruelty.
Separation is the preferred ground for an uncontested divorce: separation is the easiest ground to prove (by affidavit stating the date of separation) and is the least likely ground to require a court appearance.
Adultery and cruelty both require strict proof and will most likely require a court appearance. If you wish to proceed on the basis of adultery or cruelty you should seek the advice of a lawyer.