Netty, a lot of your synastry looks good-- with the problem of your paired moons and paired suns disconnecting. Also I think I'm picking up a bunch of quincunx inter-aspects. These are not harmonious like the trine or stressful like the square: sort of like the itch you can't scratch. Irritating but not to the degree that you have to Do Something about it. But there is a lot of compelling stuff in this relationship, such as his Juno (the marriage asteroid) conjuncting your moon, and his DC conjuncting your sun.
But I am struck by your comments about needing to find yourself. With your moon in Gemini square Mars and Aries rising, there's a lot of commitment reluctance in your chart. Also, you've got a lot of earth in your chart, and this man's sun square Neptune and major water element may seem a bit too idealistic and impractical to you.
Similarly, a lot of your composite looks really good. Many women would envy your moon conjunct Juno in the 7th house! Sun conjunct Mercury-NN suggests a lot of potential for growth through communication. Venus sextile Mars reinforces the romantic/sexy nature of the relationship (whether you've acted on this or not,) Sun square Mars can indicate tension.
I've seen long-marrieds with worse synastry, but you really have to do what you think is best for your life. You'll break his heart and he will never forget you, but if you're going to leave the relationship, I agree with the others. Give him the courtesy of the best explanation you can come up with, but do it.
Waybread, I very much appreciate your persepctives and I envy the diplomacy you have as a teacher.
Sometimes you go kind and sometimes you don't. Sometimes the cream comes at the top early and this gals chart reeks of what she speaks. She even admitted it. Pisces usually gets the red flag first or the green flag later out of fear of someone hurting a pisces feelings. It's no different for Sun through Saturn. Especially Saturn tho - they are the most forgiving and most hurt of all - Saturn in Pisces. It's a shambles, really.
Remember - querant has nodal conjunct and as already stated that she indeed cheated, gambled out of relations - and as the saturnian knows -
it takes one to know one. The ultimate 7th Capricorn vs. the Mars exaltation in Capricorn.
My first and only husband, now, at age 50 - has Saturn and Venus in Pisces - opposing his Mars Uranus Pluto Virgo stellium from his 7th. My Merc is opposite my Uranus and I have a Moon Pluto conjunct in Virgo.
There is no soft easy chair for this bunch - especially in joint 7th house matters or rulers. - 12 steppers need only dine and dash to get out of this one. If my poem wasn't enough proof - then maybe watch the antithesis - Lady & the Tramp Disney circa.
No one has distinguished if her other is the Jupiter hopeful pisces or the deluded Neptune one. Not that there's much a difference in annoyance factor.
I'm here, but I'm not here - I love you but I must disappear into the sea - Please await me lovingly, as I will you.
Get rid of that early unless you have a real axe of guilt and forgiveness to bear.
Let it be a mutual mars, sun - the combust of fire that hits water and creates steam and then everyone can breath better.
One must never worry to buckle to a Virgo or Pisces - although they can make your life a living hell - they will never break you like a Saturn or Moon -
all the things you never got.