It is an adjective that has two meanings. The first is "to be sweet" and it is used to describe a taste/smell similar to that of sugar, or a situation in which something is attractive. The second meaning is "to be naive" and it is used when you underestimate something or when you are easy on someone.
My girlfriend is always late for our dates, but I've never been angry with her. My motto is to be hard on myself, but easy on others.
- Meg: コーヒー以外に、何か頼んだ?
Did you order anything besides the coffee? - Amy: ううん。ケーキが焼きあがったみたい。甘い匂いがする。クレープを注文すればよかった。
No, I didn't. It seems like some cakes are just baked because they smell sweet. I should've ordered a crepe. - Meg: そうだね。前食べた時、甘くて美味しかったよ。
That would be great. When I ate it before, it was sweet and really tasty.
- Meg: お金もないのに、どうしてアパートを借りたいのか、全然理解できない。
I really can't understand why you want to rent an apartment even though you can't afford to do that. - Ben: お願い、お金貸してー。できるだけ早く返すから。お母さんに断られたから、もう頼める人はお姉ちゃんしかいないんだ。
Please lend me the money. I promise I'll pay you back as soon as possible. You are the last person I can ask because mom denied my request again. - Meg: 考え方が甘いんだよ。家族が助けてくれると思ったら、大間違いだよ。
The way you think is so naive. You're making a big mistake if you think you'll get any help from us. - Ben: んー、ごめん。ただ自立したいんだ。
Hmmm, I'm sorry. You're right but I just wanted to be independent. - Meg: なるほどね。だから、お母さんはベンを甘やかすのを止めたんだ。まず自分でお金を稼いで、自立しなよ。
I see. That's why mom stopped spoiling you. So you should earn money first and then try to be independent.