Wouldn't a wedding with either of those songs at its launch be at high risk of going down like a stone, once it hits a rough patch?

Here's a thread with some better choices, notably "Come Write Me Down" (AKA "The Wedding Song"). We had that one, and it'll be forty years next month. (What I like about it is, it's got a quarrel and a reconciliation in it, and that's a good start.)