i own a rabbit heh
Your second point is just as bad. How on earth does being in a relationship narrow your list of friends? It's your choice if you want to spend time with your girlfriend or boyfriend over your mates. My last relationships had absolutely no impact on my friend list. In fact, if anything it got larger because I got to know my girlfriends friends and their friends, etc.
Honestly being in a relationship at a young age is perfectly okay, and it angers me greatly when people say that young people can't 'love' or 'don't know what love is.' That's implying you can only experience love at a certain age which is definitely not true, because I know for a fact that I've experienced love at the age of 13. If two people are happy together then it's fine, whether they're 10 or 18 or 60.
Next, experiencing relationships at a young age is just setting you up for future relationships. You learn from mistakes, you learn how to talk to the opposite sex and develop social skills. You learn what a relationship entails and gain more confidence in yourself. I'm sure someone that is 25 and never had a girlfriend before wishes that they could have had one at a young age.
Basically no, I don't think it's stupid.