1. A man's best friend can call his girlfriend if he is in trouble. A man's girlfriend will not be offended by the phone call if she truly knows you're his best friend. But if she feels like you are hiding your feelings behind your "best friend" title and it later comes out, she will feel betrayed by you. So get ready to be on the next episode of "Jerry Springer" or "Maury," because that is the road you are headed down by crossing that imaginary line, without being upfront and honest with all parties involved. 5 Signs You Are A Dating Snob
2. A man's best friend can hang out with his girlfriend or potential girlfriends. But obviously, if you're his best friend-turned-girlfriend, he will not feel as comfortable about you knowing about or hanging around with other women he may find or has found attractive. This will undoubtedly create uneasiness in your relationship.
3. A man can tell you about women he's interested in. Men often confide in their female friends in order to get a woman's point of view. Should he proceed or not? Telling his girlfriend about other women he likes may not work so well, unless you have an open relationship or these are women you both would not mind getting to mentally and physically know.
4. A man can listen to a mouthy best friend because you are not emotionally connected. You can always hang out and speak up with your best friend and let an intense situation cool, with no love lost. It's not quite that simple if the person is a girlfriend, especially if you live together. Every decision you make becomes critical and one you have to face because of the physical and mental connection.
A man can't run away or dismiss himself from a woman he is in love with. He loves his best friend, but he is in love with his girlfriend. So whether he likes it or not, he will have to deal with a mouthy girlfriend, which takes the tension to a whole new level.
5. A man's best friend can go out of town with her girlfriends or guy friends. This should be no problem at all if you two are strictly friends. It will not be easy, however, for his girlfriend to just waltz out of town with her girlfriends or male friends, without a fully documented explanation.
6. A man's best friend can have the spare keys to his home. Girlfriends are usually too nosy early on in a relationship. For example, a man might be reminiscing by looking at an old photo album of an ex that he just happened to leave open while he was rushing out to go to the airport. A best friend would just look and say, "I remember her" and close the book. A girlfriend, on the other hand, may want to know "who, what, when, where, and how?" She may even draw the conclusion that his business trip is really a rendezvous with this old fling.