A male colleague sends me text messages every day, all of which are irrelevant topics. If he wants to be boyfriend and girlfriend with me, I'm not interested.

Since he didn't mention it, you can take a stand first and imply that you just want to be friends with him. Don't delay this kind of thing. He must want to chase you. Tell him not to waste time on you earlier. if

Do you think it's okay for him to be friends? You can joke with him and ask him to introduce you to a boyfriend or something. If he says yes, you can laugh and joke, "Stop joking, we are not suitable at all". If he still tells you seriously, you can also take the opportunity to refuse him seriously.