So I found a universe where cheerimac happened, though it's kind of implied they've been under the effects of the love poison since season 2. All of ponyville has actually, the CMC spiked the water supply after the spiked punch didn't work, then they fell in love with their own butts when they looked at them to check if they got their cutie marks. That episode ended without that problem getting resolved.

What's funny is their engagement got overshadowed by Rainbow Dash's marriage to her kitchen sink and that relationship had nothing to do with the love poison.