Tunnel - represents the vagina, womb, and birth. Thus it may refer to a need for security and nurturing.  Alternatively, it indicates your limited perspective.

Past coworker - because of her promiscuity, you are possibly using her to symbolize how you feel about your ex-girlfriend.

Ex - To dream about your ex-boyfriend/girlfriend or ex-husband/wife, suggests that something or someone in your current life is bringing out similar feelings you felt during the relationship with your ex, or that you are finding yourself in a similar situation that you do not want to be in. The dream may be a way of alerting you to the same or similar behavior in a current relationship. What you learn from that previous relationship may need to be applied to the present one, so that you do not repeat the same mistake. Past lovers may also highlight the positive experiences you had with that person.
Alternatively, to see your ex in your dream may also signify aspects of yourself, or feelings, that you have 'crossed out' or neglected.

Balloon:
Positive: celebration and festivities. You need to acknowledge your inner child.
Negative: indicates declining hopes in your search for love.  Balloons also represent arrogance and an inflated opinion of your self.

Ascending balloon - signifies frustrating conditions in your life in which you are seeking to rise above, also a desire for freedom from daily problems.

Descending balloon - suggests feeling disappointment, and falling hopes.

Red - Red is an active, affective color, full of passion and emotion. It may symbolize passion, luck, joy, happiness, energy, action, sexuality, revolution, warning, danger....but also hate, anger, sin, greed, irritability and will power. As the color of blood, red is also the symbol of life.
A softer red is a symbol of love, mercy and compassion.
Light red stands for warmth and affection.
When intense, red can also indicate hatred, sin, rage.
Dark red is a symbol of passion, greed, energy and anger.

White - White is feminine. Symbolizing virginity, but also emotional coldness and immaturity. Also, purity, well earned success, honesty, virtue, innocence, peace, happiness, joy, transformation, cleanliness, dignity, awareness, clarity of mind, hope, and light feelings. White in a dream might possibly be a reminder to resolve special situations and problems.

Table - suggests assimilation, or "coming together" of varying parts of your personality. It could be that you are working on becoming aware of your own multidimensional nature and are attempting to become a more harmonious individual.
Also, the table represents nourishment, friendship, unity, and refers to your social and family connections.
It could represent emotionally charged events, such as a family dinner, contractual negotiations, or pleasant/unpleasant meetings.
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I would say your dream is the anxiety you're feeling about your ex-girlfriend. You want to be with her, but you're pretty sure the old hurts will be repeated. Your subconscious is telling you to move on, and not repeat the same thing.

Hope this gives you some insight.

Best wishes!