メアリーにはつい甘くなってしまう。

at (place, time); in; on; during; to (direction, state); toward; into; for (purpose); because of (reason); for; with; by; from; as (i.e. in the role of); per; in; for; a (e.g. "once a month"); and; in addition to; if; although

topic marker particle; indicates contrast with another option (stated or unstated); adds emphasis

just (now); quite (near); unintentionally; unconsciously; by mistake; against one's better judgement (judgment)

sweet-tasting; sweet; sugary; sugared; fragrant (smelling); sweet (music); lightly salted; light in salt; not spicy; naive; overly optimistic; soft on; generous; indulgent; easy-going; lenient; half-hearted; not finished properly; insufficient; not satisfactory; inadequate; loose; mild; tempting; enticing; luring

to become; to get; to grow; to be; to reach; to attain; to result in; to prove to be; to consist of; to be composed of; to succeed; to be complete; to change into; to be exchanged for; to play a role; to be promoted; to do ...