Someone whom you have a sexual/romantic relationship with
Are you looking for unconditional love?
Thinking about romance or passion?

Dreams about your ex may revolve around specific emotional needs that partner represents for you - are you going through a similar emotional issue right now?
May be expressing feelings about your ex that you never fully dealt with - perhaps you still need closure?
What does this specific person represent to you? Do you they remind you of a specific time in your life? Do you they remind you of someone whom you used to be?
Dreams about our ex's can be about wish-fulfillment, resolving old issues or reliving past memories.  We have strong emotional feelings and ties to our ex's and so dreams of them could be expected to be powerful and full of passion, but rarely are they 'prophetic' dreams, indicating a reunion with them again.

See also 'Boyfriend' or 'Girlfriend'

What does a Boy in a dream mean?

A Boy in a dream can represent:
Yang
Youth

See "Child" and "Male/Masculine"