I believe every relationship has the potential to work. There are some relationships which just flows and don’t seem to need too much work while there are others where you sweat, fight and invest your soul and energy to make it work. I have seen the latter case where the couples get married. And these couples wouldn’t have it any other way. They love each other dearly and “work” is just part of the deal for them. Also, there are some couples where things are too “smooth” for them and they broke up eventually as the relationship was too dreamy for one or both of them.
Anyhow, when I think of a relationship requiring work, I think of one or two of them being aware of a sticking point between the two of them and making changes or adjusting themselves so that the relationship can flourish. For example, your partner may be a comedian that’s in the process of trying to make it big and you are a businessperson who thinks of being practical and getting ahead in life. Both of you seem to have different life directions/goals. For the relationship to work, there needs to be an awareness of it and changes of some kind, say changes to your/your partner’s/both of your mindset, spending pattern, etc. These changes are what I meant by adjustments.
Let’s see how much adjustment is potentially needed for Sagittarius in a relationship with another zodiac sign a.k.a. Sun sign.
Remember, the above is just one of the many elements to a successful relationship. Every relationship is different and special and can certainly work if both of you wants it bad enough.
All the best,