I think part of the problem stems from the fact that many couples, especially new and young ones get ridiculously obnoxious, juvenile, and in your face about how great and wonderful it is that they are together. For a lot of single people, it's like "yeah I'm happy for you". Five hours later and the same couple is still being overly cute and obnoxious about their love for each other, it's no longer cute and you just want to say" I get it, now stfu and get over yourselves". Admittedly, some single people let it get to them a bit too much. But then again, some couples really should tone down their public displays of affection too. I love my fiance but we have enough class not to engage in a full on make out session in front of single friends or in the middle of a grocery store.