Yeah, what is the difference between two lovers in a committed relationship and a pair of newlyweds

God's involvement, without marriage is without Him, look more into what the bible says about why we marry

should we just give them up like a puppy found on the street when they want to leave, without any emotions?

I don't know what you're talking about here.

You said you don't get "emotionally ruined" (which may be extreme, but at least extreme emotionally disturbed) after losing a love, someone you let into your inner circle and trust unconditionally; then I would argue that that isn't love, to be ok with someone that meaningful leaving your life.

Flee from sexual immorality

I'm not engaging in sexual immorality, though, there's nothing immoral about being physical with someone you love.

Completely wrong, both biblically and just in definition. It is extremely clear what is sexually immoral, it is up to you to think whether you are better than God on coming up with what God is okay with us doing in sin.

Sexual immorality

From the Greek por·neiʹa, a general term for all unlawful sexual intercourse. It includes adultery, prostitution, sexual relations between unmarried individuals, homosexuality, and bestiality. It is used figuratively in Revelation with regard to a religious prostitute called “Babylon the Great” to describe her consorting with the rulers of this world for power and material gain. (Rev 14:8; 17:2; 18:3; Mt 5:32; Ac 15:29; Ga 5:19)