Evie,
I think money you lent him is the issue here. Saturn is you and the money, in fall of Moon, so something about you is harming him. Moon right in your 2nd house shows what he is concerned with. Second house according to Frawley is also house of self esteem, self valuing and partner's esteem or value, so the emphasis on his and your 2nd house makes sense here. Men generally want to be the providers, their jobs are important and taking money from others hits them hard, its like they loose their masculinity, what men do for work defines them. So I believe he is feeling not so good about his place in the world. Moon just opposed Mercury, which may show your recent argument or recent issues. Saturn (you) is the superior planet and him being the Moon, its quite inferior. So perhaps to him this relationship is not balanced, not equal...
Mars on his ASC is in cancer, its mute. So there is anger and frustration but more of an inner frustration and turmoil. He is quite upset with his own situation and therefore ended things with you. Just thinking like a man would, a lot of men retreat, I think when they face problems. Women talk to others to get emotional support, men don't. If he is feeing less like a 'real' man who can protect and provide then he probably would not want to continue with you unless he can see something change regarding his finances and work.
I think give it a few more weeks and I think you will be back or at least talking but not sure about the quality of this relationship. Mars will apply to Saturn, trine. That's the timing. (I take Mars as his cosignificator due to its placement at 7th cusp)
hope this helps! Let us know what happens
