How do you respond when someone asks you on a date?

Tell him, I like you, but I want to get to know you better before I commit to a relationship. Lets hang out as friends and see what happens. If you want to say yes, but are not ready to have a relationship yet, you could say I want to date you.

Is it rude to not reply to a DM?

Whether your DM is coming from someone you know or someone youve never met, I got you covered when it comes to sending a nice let-down message. Also remember that if you dont know someone (or even if you do), its always OK to ignore an Instagram message.

How do you respond when someone asks you to be his girlfriend?

If you like to be his girlfriend, say yes. But, if you dont, then tell him the truth and say no. Never beat around the bush. Never engage him into petty nothings or entertain him and make him think that youre also interested when in truth, youre not.