第一句：反正我想娶她。 the last sentence is incorrect

反正正确的用法------ unacceptable, --->反正...是正确的用法, ...总（是）正确的用法 (反正, adv., = anyway, whatever..., no matter what/how...) 反正我想结婚她。---- unacceptable ---> 反正我想和她结婚 In Chinese 结婚 is untransitive, so you have to say some A marries to some B, or A and B get married. 不管怎么样反正我不抛弃你。---- acceptable, but not very idiomatic, ---> 不管怎样我都不会抛弃你 反正我硬顶继续学习。---- unacceptible, uncertain about what you are meaning 无论它允许不允许，反正我以自己的决定为主。---- perfect with the usage of 反正， the latter part of the sentence may have better expression though 不管我们越来越老，反正我爱她。--- unacceptable, ---> 尽管我们越来越老了，我还是爱着她

谢谢

应该是 我想与她结婚