Notice his body language around you. Non-verbal communication shows more than words, sometimes. Does he cock his head to one side while he's talking to you? This signals that he's interested in what you're saying. If he leans in while you talk it means he's listening closely. Good eye contact is a good signal of genuine interest in your conversation.
Talk about personal things or ask her about things you don't know. If she responds with interest and tells you openly about her personal life, she may be interested in dating you. When she talks to you, if she constantly refers to a future involving you, she probably wants to date. Questions like "Can we go to Paris some day?" show that she sees herself with you for a while.
Determine if you've been talking or communicating more and more. If you call each other or see each other very frequently and have slowly been spending more and more time together, he probably wants to date.
Blow off a scheduled meeting or get-together and see how she reacts. If she immediately wants to reschedule or seems very curious about what you were doing instead, she probably wants to date. It's a good sign that she feels entitled to being with you, a signal of wanting to date.
Introduce him to your friends and see how interested he is in getting to know them. Ask to hang out with his friends in his element to see how he treats you. He may introduce you as his girlfriend, even if you've never talked about it. Sometimes you may be dating without having had this "talk."
- Sometimes close friendships can seem like they're leading up to dating, but they this isn't always the case.