Too much love required depletes love. So is love like self-restrain, the latter being a limited resource?

I remember when I was younger, I was a very very nice person! Sensitive, giving, accepting, sensitive, giving, accepting, sensitive, giving, accepting (at least I think I was, as opposed to wasn't). In a way, the people around me made me feel that it was natural and very worthy to act as such, and I was quite happy despite _____________ sometimes. I don't know if it's age, or experience, or the combination of both, or just the environmental differences, somehow, the patience, the acceptance inside just wears off, bit by bit. Situations get more complicated, people get more trying, and suddenly, or not so suddenly as it is gradually, I realised how selfish in giving love and patience I have become. Suddenly (or gradually, it doesn't matter!), it doesn't seem that worthy anymore. Not at all. Weighing down. Pulling down.

But of course, it'll be difficult to withdraw from family and very old friends, after being conditioned to love. It's just... the newer. There are Nices, but Tryings, Rudes, Assumings, Grouches... They tend to stay well outside. Am I to be blamed for this partition?