My lover is indifferent to me, and sometimes even sends messages without replying. Should I give up? . . .

No.

First, maybe he is busy.

Secondly, maybe he is getting tired of your feelings.

Thirdly, maybe he is not good at expressing himself. I think you should find an opportunity to explain these issues to him face to face. Don't blindly choose to give up. If you love him, you will definitely regret it later.

Extended information:

A lover is a person who falls in love at first sight but hates seeing each other later. He cannot be a legitimate friend or a true lover. A lover is a love-stealer who is in love with you till death, but at the same time lives a peaceful life peacefully. A lover is a liar who talks sweetly to you on the one hand, and on the other hand, he makes elaborate excuses to go back and make excuses.

A lover is your soul partner, your emotional sustenance, and your ideal idol. Lover, if you can withstand the storm of love, the experience of life and death will be something you will never forget for the rest of your life.