Well there are a bunch of reasons why some people can't find love? This is a loaded question
I do agree the answers lie in the self and your choices/emotions/fears, but also your family, environment and all that play into it. And of course astrology and your natal can play a role
For both a woman and man a bunch of reasons such as:
Socially: Fear (a whole bunch of reasons for it: past heartbreaks, fear of giving up losing freedom), insecurity, "bad luck" "bad timing," "poor choices in men,"
Astrologically, Afflicted Planets in:
Woman: Saturn, Sun, Venus, Mars, Pluto, Uranus
Man: Moon, Saturn, Venus, Mars, Pluto, Neptune, Uranus
Woman/Man:
Saturn: I have been reading Liz's Greene's Saturn: A new look at an Old Devil, and she points to Venus in aspect to Saturn as an afflicted in a woman's chart. She explains how in a chart a woman may reject or be insecure about their femininity in their chart. They may work against it or go to extremes (like a Femi-nazi or a prostitute). Fear is a motivation in this case
Sun: Sun represents father, but what if your father died at a young age or you never met your father. Your early upbringing and lack of a father figure or role may lead you to choose bad/poor partners; especially when afflicted.
Venus/Mars/Moon: I know we look to Mars for what a women is attracted to in a chart, and Venus for a man. What if the women has a strong mars is "too aggressive and combative" in a relationships. I know its a bit outdated thinking but men oftentimes want a feminine woman. and a women with a strong mars may not give that to him. Perhaps an afflicted moon can work the same way. It is possible to find love but are what mmn secure enough in himself will be willing to after this mars women. An afflicted venus in a man's chart may may him effeminate and he may be viewed as weak. Women do want a strong man that can provide and control them (in other ways of course

) Liz Green talks about Mars aspecting Saturn in a man's chart and how this may produce a man who's ruthless/cruelty, questioning of sexuality because they may reject or be insecure about their masculinity in their chart (kinda like venus aspecting saturn in a woman's chart)
Pluto/ Uranus/Neptune: Afflicted/strong pluto can make a mate too intense, controlling and obsessive..... an afflicted/strong uranus may make a person too unstable, rebellious, and too independent in relationships; while an afflicted/strong neptune may make someone too idealist, needy, unrealistic in love.
I know this is general chat so i gots to keep it general

I think its alot about choice and knowing yourself and who you are. The choice to move past your fears and insecurities, to not hold back and give love a chance. Sometimes common sense may be lacking (not to be mean). Some people don't know themselves or what they want (and need) and they make poor choices and do stupid things and miss opportunities. We all make mistakes, but some people make them frequently to the point where you think they must be stupid/delayed.
To be fair, sometimes it not them, and got to with who they attract (or not attracting). Sometimes they are confident, beautiful people who just can't catch a break, bad/timing, being ignored/denied constantly, who's partners don't know their worth, etc. Perhaps karma can come into..... IDK... it could be karma (i got to research karma more!!!) Who really knows??