What is the religious ruling on establishing a romantic relationship with a girl, reaching the point of exchanging kisses and having the unexpected occur, while there is a sincere intention to marry?

What happened between you two is a result of Satan's enticement, as he beautifies glances and speech leading to the commission of what displeases Allah, as stated in the verse: (O you who have believed, do not follow the footsteps of Satan. And whoever follows the footsteps of Satan - indeed, he enjoins immorality and wrongdoing.) [An-Nur: 21]. Allah has forbidden zina (unlawful sexual intercourse) and the paths leading to it, saying: (And do not approach unlawful sexual intercourse. Indeed, it is ever an immorence and is evil as a way.) [Al-Isra: 32]. He also commanded lowering the gaze and not being alone with a non-mahram woman, and that a woman should not speak in a soft manner nor go out displaying her adornments. If you wish to marry this girl, then both of you must repent, seek forgiveness, and increase in supererogatory acts of worship.