Church is the best place I can suggest for you. My church's youngest single female attendee is about 85, but that hasn't stopped me from making friends with many of the young couples in the church, and some of them have become good friends. The closest friend I have is someone I met at the church I worked at and became friends with he and his wife. Even now, separated by 6 hours of drive time, we check in often with each other. He's very comfortable with his wife and I also being friends, and most guys, knowing that your intentions are true and confident in the unity of their marriage would have no problem with you befriending their wife (which is why I'd suggest becoming friends with the couple first, and her after that trust has been established).
Work and/or school are two other obvious ones. You don't have to strike up a conversation on their feelings on the roles of men and women in marriage in your first conversation. Find someone with some similar interests. I used to hit up a Christian dance club with a co-worker as friends. I've also attended many sporting events with a female friend. Simply a matter of finding a connecting point, and that is usually fairly easy in water cooler style conversation.
