Hi, I'm not as great at reading charts as many people on here, but the only thing I can think of is that the ruler of your 7th house (house of long-term relationships/partnerships) is squaring both Uranus and Saturn. Ruler of your 7th house squaring Uranus (the planet of things such as sudden and unexpected changes), so your relationships end as quickly and unexpectedly as they start. You likely notice that you meet a potential date out of no where and when you least expect it, you date for a bit, and then suddenly something happens and it ends. And the cycle continues.
Additionally, your Venus is in Aquarius (the sign ruled by Uranus) and it is in the 12 house...do you, or have you ever had, have any secret relationships? Maybe a relationship (or more than one) that you kept a secret for some reason? Maybe it even represents that you attract Neptunian guys -- guys who are wishy washy, don't know what they want, are moody, and deceptive (liars, maybe they cheat, etc.)? You probably attract guys with Aquarian traits (Venus in Aqua and your 7th house ruler squares Uranus), and Aquarians are typically independent and don't settle for a very serious relationship so easily -- they like their freedom.
I also notice that your ruler of the 7th house squares Saturn, which can delay long-term romance or make it seem next to impossible for you to find a long-term partner (as you describe).
Your Venus also squares Mars and Pluto. I wonder if that means that you attract obsessive, controlling, angry, or even abusive types with whom you can't really make a long-term commitment with? Your Venus is in positive aspect to Jupiter, so you likely don't have any problem attracting guys/dates, but those other aspects make it difficult for you to find the right one and stay with them for long. With Chiron in the 4th house, I wonder if you didn't have a troubled or difficult childhood or family that makes you a little standoffish on a subconscious level for fear of getting hurt? That last part is just a guess, though. Good luck! I hope you find someone.