There seems to be a bit of a spate of proposals at weddings at the moment. I get it, you’re in a romantic setting, looking your best and thinking about love and commitment. If you’re both close to the bridal couple then a lot of your family and friends might be there to share the moment.
Seriously though: stop. Think about how you would feel if one of the biggest days of your life so far, that is meant to be all about you, is interrupted by another couple standing center stage and grabbing some of the limelight for themselves. Then, pick another time and place!