It takes a lot more than knowing a Sun sign to be able to answer a question like that. In my astrology articles, my efforts are to teach people the truth about astrology. Every planet and your Moon is in an astrology sign, and there are 12 houses which all have meanings. The distance between each planet matters. So does the Date, Time and Place of Birth.
But the quick answer you want is that it will be a challenging relationship. Capricorn and Libra are both leadership signs that are very ambitious people. The Libra woman thinks she's a Queen, and expects to be treated like one. But she is generous, friendly, and loves to socialize. She would do well in the hospitality industry.
A Capricorn man is stable and likes his security, but he is a hard worker. He will appreciate the business knowledge the Libra woman has, and also the time she takes to look good. He's sensual, but mostly in private, and she likes to get attention from her man. If she accepts it when he's ready to give it, they can basically understand each other. He's a lot more down to Earth, but needs a little of her vitality to liven up his life.
Based on that, it can work. Sometimes we need challenge and Libra and Capricorn are what we call "cardinal signs of change." So you will be forced to make changes in your lives to make it work. But sometimes that is why a soulmate comes into your life! I think it has potential.