You are a woman who goes into a relationship hoping it will lead to something serious, as you plan for the future. Cancers are gentle and fun, they like to try new things, and are practical and kind. A Sag man is intelligent but not so likely to be looking for a long-term relationship; he's more of an in the moment kind of guy. He's restless, and so is his Virgo Moon. He keeps a tight leash on his emotions and can be overly critical, which will hurt your feelings.
Your Libra Moon means you crave a partnership; you even like them in business. The Cancer/Libra combination means you are ambitious and have definite goals. He's more of a person that goes with the flow, and with the Virgo Moon, he's kind and practical. But both Sag and Virgo are what are called mutable signs, and I don't see him in this for the long haul.
It's not by any means a terrible combination. You may have other planets that work well together and can have some great times ahead. But if you are getting too serious about him, I have concerns you may get hurt. You know what you want out of life, and he is going to change his mind many times. Maybe see how it goes for a while, but don't try to change him into what you want if it isn't going where you want, that never works. Best Regards.