For what it is worth I think this is what is happening to you.
Like most men your expect action = predictable result from an objective stand point. Regrettably women do not operate this way, so relationships with women require a man to set aside his natural expectation tendencies and adopt a DJ philosophy. This is not PUA stuff, or relationship dating stuff like you find with life coaches like Corey Wayne. What is happening with you is NOT DJ philosophy...
DJ Philosophy is simple, and it starts with you. You have to be the very best man you can be. You can not get any woman you want: but by being the VERY BEST you can be you will naturally increase the percentage of women that will be interested in you. You only really want to spend time with women who are willing to chase you. Otherwise you live your life for YOUR happiness. If you are not happy because of your relationship, you are focused on the wrong things. You really should focus on those things that make YOU happy and what YOU find enjoyable... and invite women into YOUR world.
You run into chicks with high interest and it goes nowhere... there are a couple of reasons why this might be happening. First, you are not acting like a man in the dating process. There are a number of threads here on what to do during the dating process to build interest, and if you are looking for a relationship, Doc Love is about spot on, except if you are not banging them after 3 dates then you are pretty much done. Second, there might not really be anything wrong... what you described is pretty much my dating life, I date chicks with high interest, it lasts for a few months.... then when I won't commit to exclusivity they move on. I have one women in my life that I have been seeing longer than 3 month, and this has been going on for 2 years now. We hook-up every couple of weeks, and I go with her to formal occasions when she needs a dude that looks good in a tux and can impress her friends. She does not want anything permanent, just sex occasionally and a dude that will not embarrass her in front of her wealthy patrons. Most women are not like this, they are looking for a plow horse... preferably one that they are attracted to.
I am not a relationship guy, so please take any relationship advice I give with a grain of salt. But in my experience women who are willing to chase you are two levels lower than you are, those that are only level below, will chase IF you show them interest. Women who are at your level will only chase you if the timing is right (they just came off a break-up, they just hit a 5 year anniversary (i.e. 25, 30, 35, 40 ect.), they've just gone through a significant emotional event of some kind). Women who think they are better than you WILL NOT CHASE YOU. You can get them for a little while, but it will never last.
If you are a 9, 8s and 7s will chase you, 6s won't bother unless for some reason they are super confident, 5s or less will not even try. Depending on the circumstances, 9s will chase you as well. AND you might get luck with the occasional 10, but don't waste your time... if it happens it happens, but trying to get someone out of your league is the stuff of BS romantic comedies and that sh!t just does not happen. This BTW is why chicks get FVCKING MAD AS HELL when a guy they see as WELL BELOW them, trying to hit on them... Because women would NEVER try to get a man that is well above them, they assume men are the same way. So in her mind you are insulting her if she thinks you are well below her in status when you hit on her.
Just be the very best you can be and your goal in life should be that you are going to be better tomorrow that you are today, and try to find hobbies and interests that will make you a better person. Do what makes you happy, but if what makes you happy is getting drunk or high every night and playing X-Box, just do not expect too many chicks to be interested in you.
