Four words that never mean what they say. Nobody requesting favors is seeking help; rather, they are assigning obligations you did not agree to. Do me a favor means: sacrifice your time, your limits, your plans; we'll label it a favor so you won't say no without being the jerk. We will enfold obligation in the vernacular of friendship. We will present exploitation in an offhand manner.
Translation: join in my lies. Each favor was really psychological effort masked as a modest request. The worst ones begin with it would only take a minute. It always takes not a minute. Resentment you swallow for an hour, a day, a year because you already agreed and pulling out now makes you the bad guy.
Friends become trades as follows: Do me a favor. Love turns into a ledger as follows. One day you awake and see you've been doing favors for everyone except yourself and no one is keeping count but you. She now learnt to listen differently. Do me a favor means check the limit. Test it for integrity.