have you ever regretted to get married (not to a specific person, but to the action of marriage). Or have you ever regretted to have kids?

I'm in my early 30s and I feel being pressed to get married by family and sociocultural factors. For a long time, I had been single. My parents would say that my life is incomplete if I'm single. but now I'm in a relationship, I honestly miss my single life a lot. my girlfriend is nice in general, but she is kinda materialistic and lacks aspiration. I'm worried about our potential marriage.

I feel the happiest in my life when I surpass my old self or when I learn something new. I really want to achieve something in my career (for example a successful startup). I want to write good programs and play good piano. I have no motivation to pass down my gene, as there must be millions of people smarter and stronger than me. I'm not able to explain the meaning of life, so I think I shouldn't pass this head scratching question to other people (my kids).

All I want to do is broaden my knowledge and apply it to something useful. This seems to require solitude, so that I can focus on the tasks. My parents thought it's easy for me to say when I'm young, saying dying along is miserable. they think raising kids is a collaborative project between the couple and will stabilize marriage. But I think these purposes are selfish.

Do you think marriage is a must? have you ever regreted to get married? has marriage improved your career or goals. have you sacrificed a lot to maintain a relationship.

Do you believe that productivity fades after marriage as reported by this paper?

http://personal.lse.ac.uk/kanazawa/pdfs/JRP2003.pdf