The thing is, you have to be really really aggressive to get Bethany to rival you. I've been a pro-Templar/pro-Chantry character as well and still didn't get her out of friendship. Unless you're a total jerk, Bethany is going to be your friend no matter what.
Act of Mercy: When talking to Grace, choosing "I won't help you" yields (+5) When talking to Sir Thrask at the end, turning the mages into the Circle yields (+10)
Long Way Home: When Merrill opens the barrier with blood magic, say "It did help us". (+5)
Bait and Switch: At the end of the quest, agree with Fenris by saying, "I know the risks" of cooperating with a mage. (+5)
Birthright: After finishing the quest, talking to Bethany and choosing "This will never be home" leads to (+10)
Enemies Among Us: When talking to Knight-Captain Cullen to end the quest, choosing "You're right" (+5) and "You can't take any chances" (+10)
Shepherding Wolves: Refuse the mission (+5)
The First Sacrifice: If you sleep with Jethann you receive (+5)
PS. That's just a part. I don't see any jerkiness here for a pro-Templar character.