Meh, I think the best time for anyone to be in a relationship (whether it be male or female) is when they realize that they can be perfectly happy being by themselves.
This means they are not actively looking to find the "one" (if there is such a thing). They just let it happen. If it happens, it happens. If it doesn't, it doesn't, and you move on until you notice someone else.
That being said, it still stings when you are very attracted to someone, and it isn't reciprocated, but yes, I agree -- there are a lot of people out there that don't think about anything else, but getting an SO. Which is sad. I think that you need to leave a little room/leeway for a little angst, but otherwise, yeah it is sad.
Honestly, though, girls tend to complicate life. Unless I find another girl that I am compatible with, I plan on being happy single. This last time was tough for seperate reason unrelated to this girl though (someone I thought was a lot more upstanding of a guy than he actually is, was doing something pretty f@#$%# up IMO <it made things messy with the girl> ). But yeah, some of these people need to grow up. OP, you have to realize that a lot of the posters now are in their late teens and early 20s and have not had to really grow up. Give them time and a chance to go through hurt and trials that are much tougher than relationships, and that will put things into perspective for them.