Every Class has a couple of abilities geared for support but I've found Engineers and Outlanders to be more effective for playing support. I've seen a few "paladin" Engineer builds that use Healbot and Forcefield for survivability and Immobilization Copter and Tremor for debuffs. Add in that pet who has an AoE silence skill (forgot which one) and you and your wife will be practically invincible, and fighting mobs that can't use their special attacks/spells or let alone move.
I Haven't seen any full support Outlanders, but you could easily make a support/debuff build with skills like Cursed Daggers, Blade Pact , Vortex Hex, and Stone Pact. If you can find a way to maintain full charge, Share the Wealth would be a great passive to add with the build. It won't be as effective as being able to negate 10000+ damage every 30 seconds like an Engineer, but it'll keep you from getting bored. In the end just remind her to invest in elemental defense gear in NG+ and above. Damage mitigation takes on a huge role when elites and bosses can one-shot you with nearly impossible to avoid specials.
XI Wiki



