Hello Aristocrates,
When trying to derive meaning from dreams, I have always found it helpful to identify which events are genuine waking life events, and which depictions carry symbolism. (keep in mind that waking life events can be viewed, both, as real waking life happenings, and symbolism but it helps to know).
This prompts me to ask you to determine reality from that which is not.
If, for example, your ex is pregnant or you feel that you may be the father, if she is pregnant, then the obstacle in the river can be seen as the emotional island that keeps you from progressing further on your river of life (life as you knew it). It is clear that you wish that you could go back to a level of comfort, go back to the way that things once were, before such a possibility existed.
If she is not pregnant then your dream may be the mind's way of allowing you to to experience a life changing situation through the introduction of genuine emotional discomfort, so that you will avoid such a situation in waking life.
The dreaming mind is an incredible mentor and friend!
Either way you can see the dreams importance.
regards,
sailrmc