Because you are jealous, and feel that he is going to get back together with her.
Also, because in dreams, every unanswered question in your head comes to life, even if it was in the subconscious part of your brain. And you've been thinking about it before you went to sleep.
It doesn't mean it's going to happen though, so relax.
It means you should get back together with him.
The question is not entirely clear. A dream about HAVING the ex boyfriend's baby would be different from dreaming about a baby the ex boyfriend had by someone else.
This dream suggests the dreamer continues to have feelings of affection for the ex-boyfriend. Alternatively, the ex could represent something quite different from the dreamer's past. If the period of time when the dreamer and the ex were together was happier than the present, the dream might express nostalgia for the past in general, rather than for the ex himself.
This dream suggests that the dreamer remains emotionally attached to the ex-boyfriend and is projecting her own emotional distress onto him. The dream does not reveal any accurate information about the ex-boyfriend's thoughts or feelings.
This might be a wish-fulfillment dream, particularly if the dreamer wants to re-establish a relationship with the ex boyfriend. The dream expresses the dreamer's emotions and provides no information about the ex boyfriend's feelings.
It is obvious you are still in love with your ex boyfriend and hoping to get back together with him or it is wishful thinking that he will contact you and therefore he is on your mind a great deal so it is normal to dream that your ex boyfriend is trying to contact you. If he does not have a girlfriend then out of curiosity contact him and see if he will meet you somewhere. Take the risk.
Maybe she really liked seeing you two together, you should talk to her about how she feels about you and your ex breaking up.
This dream suggests that the dreamer continues to hold an emotional attachment with the ex boyfriend.
It is not abnormal to dream about an ex boyfriend because you once were a couple in love and have made good and bad memories together so it takes some time to get over a relationship. You are dreaming he is at a distance because he is; you are no longer a couple.
It is normal to dream about what is on one's mind. So if there are lingering feelings for the ex boyfriend, the dreams are reflections of those feelings. The dreams do not reveal anything about the ex boyfriend's feelings.
This dream could suggest that there is something in the ex boyfriend's past that needs "washed" or "cleaned up."
The dream does not provide any information from your ex-boyfriend's mother or about your ex boyfriend's emotions or behavior. The dream is a product of your own imagination, and reflects your own hope that your boyfriend misses you.