Your boyfriend must be a very important pillar of emotional strength for you. This can be a very positive thing. Very few girls at such a young age are able to find such a sturdy relationship with a boy. Now let's focus on your return to shore. This brings another metaphor with water as well.
Rivers often represent life.
The fact that there was a supervisor inquiring about whether you finished the course successfully means that you feel others are judging you - maybe a parent or a teacher. Your reluctancy to admit your failure symbolizes your unwillingness to face your mistakes and move forward. Maybe even guilt. In reality, you must face your downfalls, and own up to your responsibility. Once again, your boyfriend rescued you.