Transitioning from casually to exclusively dating can at times be confusing, nerve-wracking or uncomfortable, especially if you are unsure you're both on same page. You may be worried about bringing up the boyfriend-girlfriend talk too soon, risking scarring your date off, or too late, which may send the impression that you're not interested in pursuing an exclusive relationship. Despite these fears, taking the steps to clarify where you are in your relationship and let you know, definitively, if you're "boyfriend-girlfriend" or not.
Examine the time that you spend together. If you don't spend too many nights and weekends apart, bringing up the boyfriend-girlfriend talk may be the natural progression for your relationship. If you find that your sweetheart spends time making excuses not to get together or only wants to see you on his or her terms, the interest in dating exclusively might not be mutual.
Choose a time and place to have the conversation in a meaningful manner. A romantic dinner after dating for three months, or a day trip to the beach might make for an excellent backdrop to bring up the subject of exclusively dating.
Tell him how much you enjoy spending time with him and wait his for response. If you still feel comfortable after his response, tell him that you would like to exclusively date him and be his girlfriend.