I do not want to discount the point point made by the OP. I am sure that it is true that there are many people who reject proposed shiduchim (or after a date) for ridiculous reasons. It is likely that very often these rejections could be from the parents with twisted hashkafos who are messing up their kids lives.
However, we don’t always know the whole story and very often assumptions are made that are just not true. It could be that the rejections come for valid reasons. For example, if a girl feels she needs a boy currently in Yeshiva and you are working (your title gives that one away) then that is a valid reason to reject a proposal based on HER requirements. You may be a much higher quality yarei shomayim and better catch than the guy in Yeshiva who misses minyanim and sleeps through half of seder, but that is not what she is looking for. It could be some girls feel they need a guy taller than her in order to respect him (BTW they say that R’ Ahron Kotler’s wife was a head taller than him. She did not need the physical height since everything else about him more than made up for it)
We also need to remember when it comes to shidduchim something that is true in all parts of life. Hashem runs the world and will determine when we find our proper zivug. We need to do our hishtadlus and daven but it is silly for us to say “the reason that I am not married is that I went to a co-ed high school and girls are rejecting me.” Your job is to do your best job as a Jew and when you get rejected thank the One above for keeping you away from a machshefa who could ruin your life. If you and your roommates are great guys, the world will recognize that. There are a ton of girls (and their parents) who are probably reading this and saying “how do I get these boys?!”