It's best to explore your question from NOT why Caps seem to like you ------ but (you are the singular person at the center) AND you are the one asking this question. So, the question is not why do I keep attracting Capricorns --- It's what is it that makes you attracted to Caps!
Since we can assume that you don't ask people their sun sign---and if you do ask people ahead of time their Sun Sign, we must assume that you INNOCENTLY. become attracted to a certain kind of person...and then after a while, you conclude its not going to work.
I would propose that you become attracted, then later find out they are Caps, and then you don't get along. This also becomes complicated. i.e. Have you already decided that you actually don't like Caps, and then when you do you unconsciously scuttle the relationship without really being aware of it. So now that you've seen these "complications", I would propose a straight astrological comparison.
Gems are typically talkative, cheerful, apparently merry people who do well socially, especially in the beginning and have charismatic ways that are winning, especially in the beginning.
Caps are serious-minded, organized, almost stern, not particularly talkative, hard-working, conservative with money and on the job. They are clever, have good senses of humor. They can pick at people, (but only in fun). They will almost always come up with an "alternative point of view" in discussion and thus appear to be contradictory or argumentative.
So the Gem is initially appealing, makes the Cap smile, but after a time concludes that they talk TOO MUCH, and concludes that the Gem isn't that smart---they just love to be sociable. Since the Cap can be quiet and stern, you can see why they like Gem in the beginning.
Gemini is cute and talkative but is really sensitive when comments from Cap get cutting or harsh. Because the initial Cap reaction appears to be positive, Gem nibbles closer, then Cap does its usual routines. Gem gets hurt, then protests, Cap says Gem is being touchy and the relationship then becomes a work of effort for both. Hopefully, this helps.
When certain people don't "get along", the complications tend to arise on both sides. The above comparison is only theoretical.