Relationships are meant to be a mirror to the self...since he is dating someone else are you suggesting that you have had a relationship in the past, and are no longer involved with each other?
..of significant note are the individual nodal conjunctions with the Moon in one, and Mars in the other however the expression of energies between Mars in Aries and Moon in Cancer can be somewhat troublesome...it suggests that your desires may be quite different in life...the desires of one will not be in harmony with the needs of the other...then there is the fact of the Mars energies being opposed between each individual expression...the opposition between Aries and Libra can be quite affective to the relationship; since his trio of Saturn/Pluto and Mars in opposition to your Mars and NN, this would especially point to problems of a divisiveness nature. The Libra/Aries axis is all about relationships and resolving your individual karmic baggage; Saturn in Sagittarius has quite a different agenda than Saturn in Libra..since this relationship is apparently in the past then the question becomes one of 'what karmic lessons you learned through a relationship with him'?...
I am not specifically saying that it wouldn't be possible...I only ask why are you still clinging to hope for a reconnection? The Scorpio influence though can make for some obsessions or possessiveness, and one needs to know whether this is what you are currently experiencing, especially with the aspect of your Pluto and his Jupiter being conjoined. The Node in your 12th house and his in the third suggests potential problems of communication between the two, but also suggests a karmic pairing also. Currently with Mercury being retrograde until November 10, it does affect many of us in terms of experiencing a sense of hitting the rewind button and reflecting on the past and rethinking our own actions in the past...again your question cannot be answered directly without a much deeper analysis...there are many factors to consider, but if it is over, the onus is upon you to move through the process of letting go, which can be especially difficult with your Cancer Moon; yet the trine between nMoon and Jupiter shows the need for moving on and remembering what was learned through the prior connection. You might be better served by not obsessing about why it had to end; if it is truly karmic in nature, then the distance between you will ultimately be resolved...yet if he is now cavorting with someone else, why keep yourself trapped in your own emotional quagmire? I do wish you the best of luck in finding balance within, regarding this situation.