There may be many reasons a guy will change the way he acts around a female friend. This change is not always a bad thing. A male friend who flirts with a female friend may stop flirting when she starts dating someone out of respect for her new boyfriend. Other times, people in a new relationship spend a lot of time with their new partner, their friends may feel left out. It is also possible women will change the way they act toward their guy friends without realizing it. Whatever the case may be, the best way to handle the situation is to sit down and talk with your friend(s) about how you both feel about the situation. Remember to be open minded and let them know that no matter what they feel, you still care about them and want to be friends.