For a while I've thought that people can be perfectly happy in solitude (whatever the reason) but lately I've come to think that that is not quite correct. While there is a huge spectrum of people ranging from invtrovert to extrovert, all have the capacity for happiness of course. The main belief in my changing view is that of humans being social creatures. Relationships are important for all kinds of reasons such help, support, fun, growth, etc. Tom has touched upon this once before so I'll be good enough to continue it for a little.
Problems that arise between people are breakdowns in their relationships. It is for this reason that relationships can be a double edged sword. Yet the good definitely outweighs the bad in my opinion. The way in which to avoid the bad is quite simple. Realize that relationships are not about what you get out of them but what you put into them! Having the need to get something (love, acceptance, etc.) out of a relationship begets attachment, which is certainly not the path to growth. People grow by the giving of themselves (time, possessions, and so on). To take it an extreme, I once heard that man does not need [to receive] love, he needs only to [give] love.
Kinda short post, I might be able to say more on this topic but I'm done for now. Also, I'm doing much better ^_^