Dear Eric: About three years ago, my work friend “T” and I quickly became close. T professed her (platonic) love effusively. I, a non-trusting person who usually keeps people at arm’s length, believed I had found a new “bestie.” But, once in a while and completely unexpectedly, T goes into a “mean girl” mode. She’ll make undermining comments about my appearance, snap at me about seemingly trivial things, and act annoyed and pissed off throughout our encounter.