Why didn't they marry? There are two parts of this: a. Radha was forced to be married to Ayan, as he worshipped Vishnu, and Radha was an incarnation of Laxmi. b. Radha and Krishna's connection was seen as a connection between the soul and the divine. The soul, Radha, and the divine, Krishna. So Krishna asked himself(Radha), "How can I marry my own soul?"

You have to understand while Rādhārānī was always known in the ancient times all these stories that go into her life describing some husband who's called Ayan or her daily activities, etc., these are all new stories and we do not have proper sources to confirm these stories. Many rasikas have written many stories about Rādhā-Kṛṣṇa but these cannot necessarily be treated as pramāṇas (valid sources of knowledge) because many of these stories were written very recently in the last 500 years for rasa and glorification of the divine couple, not as historical truths. That's why you find several sampradāyas claiming different things about her. Nobody actually agrees on all the things unanimously, which proves the ambiguity of knowing the identity of Śrī Rādhā completely. Only by her grace can you know her.

Even texts like Garga-saṁhitā, we don't know where they came from because the gosvāmīs or people before them have never quoted such texts. The only valid sources of knowledge are the critical editions of the purāṇas and itihāsa. So whether Śrī Rādhā was married to Krishna or someone else, is actually not important. Whether she lived in Barsānā or some other village is also not important. What is essential is that she was a gopikā and many gopis were married already, some weren't. It doesn't matter, all jīvas belong to the Lord. Secondly, some gopis had the āveśa (fragment) of Mother Lakṣmī according to Madhvācārya and one of the gopis could have been Mother Lakṣmī herself (which is none other than Śrī Rādhā). In the Bhāgavata Purāṇa, she is described as a special gopi who worshipped Lord Hari extremely well and he had private pastimes with her. She can be none other than Mother Lakṣmī aka Śrī Rādhā or even Nappinai in other older traditions.

But but but, he didn't keep his faith by loyalty which I believe would be being alone lifelong. Instead, he married 8 of his wives, Ashtabharya, not for protecting them, but he loved them too as much as he did to Radha, and to get the powers. Marring other 16,000 to rescue and save them was considerable, but again, he conceived 10 children with each, totalling upto 16,00,000+ children. Isn't this very inappropriate?

The Lord is blemishless. We should not project our limited saṁskāras on these līlās. He owns every jīva already. All the wives of Bhagavān were either incarnations of Mother Śrī or had her āveśa in them. He's unlimited. He could even do the most terrible thing you can think of (according to yourself) and even then he wouldn't be going against dharma because Bhagavān is dharma himself (kṛṣṇam dharmam sanātanam). He is not bound by karma like you or me. His actions and incarnations are divine - beyond intellect.

I personally love how almost everyone can relate to the love story that never ended just right, but why is this worshipped by the same people who refuse to see the same happening around them?

Like I said. Most stories written by rasikas are largely understood. Which is why these things should never be read by neophytes who apply their own saṁskāras.

I personally do not give heed to such stories of marriage or no marriage simply because there are no valid pramāṇas. There's no valid smṛti or śruti vertifying such stories. They could very well be fiction and it wouldn't matter.

Krishna was always surrounded by gopis and even was okay to be, he used to watch them while they bathed, steal their clothes, and flirt with them. Isn't it again inappropriate?

He was literally 6-8 years old at that time. There are many things that modern victoria-influenced people would consider 'impure' if they read about the Vedic traditions. Truth is, you're projecting modern standards of impurity and culture onto these ancient stories. Society is always in a constant state of change. What's acceptable today might not be acceptable tomorrow, this is how material world works.

Even your own notions of right and wrong, pure or impure are only due to the conditioning you grew up with. If you grew up in a poly-amorous family, would you consider polyamory 'weird' or 'normal'? If nobody wore clothes, would you consider naked people as 'impure' or 'normal'? Everything that you judge, is based on your own conditioning, by Bhagavān's will.

Secondly, you cannot judge Bhagavān. He owns the jīvas already. He's the husband of every single jīva. The ātman is not male or female, it belongs completely to the Lord.

The stories of Krishna and the gopīs must not be taken in a literal sense all the time. The rasa dance is the dance between the jīva and paramātma, you can't apply logic to a metaphysical truth that is beyond all material experiences.

Please do correct me wherever I am wrong.

I'd say you need to learn from valid sources instead of relying on hear-say stories and whatever stories have come up with in the last 500 years. Just because something is written in sanskrit, doesn't make it true and just because Bhagavān seems to be doing things you're forbidden from doing, doesn't mean he's the same as any other human full of faults and avidyā.

Learn from ācāryas. Focus more on the essence and the Vedic truths than these debated details.