If a man suddenly has a very busy schedule, full of new work commitments, new activities and new friends that he is not introducing you to, it may indicate that he is looking for ways to avoid spending time with you. In doing so, he is filling his life with people and activities that have nothing to do with you, perhaps preparing himself for life after the relationship is over.
He Criticizes Your Looks
A man who is no longer interested in a relationship with you may not be concerned about your feelings when it comes to your looks. Women are usually sensitive about how they look, so if your boyfriend is beginning to make negative comments about what you are wearing or your weight, take that as a sign that he may no longer care.
No Future Plans
If he avoids the topic of vacations with you or events where tickets have to be purchased well in advance, take heed. If you're in a mature, long-term relationship but he refuse to discuss the future in terms of marriage or living together, it may be because he is imagining his future without you. Therefore, he doesn't want to commit to anything.
No More Sex
If a man is no longer interested in having sex, it may be a sign that he no longer finds his partner attractive. A once active sex life that has waned significantly is a good indicator that the relationship is nearing an end. At the very least, it may indicate that he is having sex with someone else.
If a man starts picking fights with you over insignificant issues, making a huge deal over mundane details of life, chances are he is laying the foundation for a breakup. After all, he can then use the "we fight all the time" reason for ending the relationship.