Clerics are great. I have lots of fun playing with my 2 Twink Healer (I have a 3rd R7 full support But She keep rotting in my Lodge)
Clerics can heal and their sp recovery is good too. And they also can have very nice dps.
You cant really go too wrong with whatever build.
But if you want to heal your GF just put in Cleric c2. Thats enough.
Put in some damage classes. Its more fun and less of a hassle when the “Healer” can dish out damage, too 
My BF plays “healer” for me XD
We are a Cleric2-bokor-sadhu2-kaba-Inqi & Wiz3Link2Necro3 combo. And we can dou almost everything. And its very fun to play together 
Cleric2 bokor3 pardoner PD is int dps with heals I heard they are very good in end game. But expensive because of all the hp pots (effigy uses lots of them)
Cleric 2 diev3
Is a very good base too. Heals and statue supports. Also int dps.
Can be finished with lots of combos
Like druid PD2 / Druid3/ priest kabba/ priest pd2
Hope you can find what siuts you (and your gf)