Understanding Synastry - Sooo many major aspects

I'm getting deeper into synastry and would love more skilled eyes on the synastry chart I'm dissecting. I figured using a past relationship (I'm Blue, they're Red) would be a great jumping point to understanding how it works. There seems to be a lot of major aspects (which I'm presuming are ultimately how and why the relationship last as long as it did) but would also love more skilled eyes to get a better understanding of what you see.

The oppositions and squares are interesting, especially our mercury opposition since we definitely had a lot of difficulty with communication and getting the both of us to communicate on the same level. The Squares to my Moon were also pretty apparent but proved to be areas where it was a bit easier to find the middle ground for communication and expression to get the both of us feel comfortable.

I'm a little shocked at the Vertex conjunct Sun, NN conjunct Venus, Vertex conjunct Part of Fortune aspects, however. I feel like this likely explains a lot of how much we stuck to each other when we were together and how driven we were to make things work. It also explains the sense of familiarity that was there as well.

Very curious to see how others would interpret this

The aspects only show you how dynamic the relationship is. If you want to know why you are together then you would have to look at activated houses which will show you major themes of the relationship.

To expand on what Muchacho wrote, if the birth times for both charts are accurate -- or even if you only have birth time for your own chart -- then it's obvious from the overlay chart why the two of you were drawn together. The other person's Sun fell into your seventh house of partnership, his/her Moon fell into your eleventh house of friendship, and his/her Mars fell into your eighth house of sex and shared resources. It really doesn't get much better than that -- the only thing which could have made it better in my opinion would have been if your partner's Venus had fallen into your fourth house.

Similarly, if the other person's birth time is known, then your Moon fell into his/her seventh house of partnership and your Mars fell into his/her eighth house of sex and shared resources. I can personally vouch for the fact that relationships in which your partner's inner planets activate your eighth house are very compelling and emotionally intense -- and they can be very hard to walk away from as a result.