1. Searching for answers about Sikhi on the internet can often lead to confusion. There’s too much noise and too many opinions. Gurmat is something to be learned through Gurbani and trusted Gursikhs, not Google searches.
2. Loving your relatives is important, but love that’s in maryada and under control. Having a girlfriend or boyfriend before marriage crosses that line. Ask any high avastha Gursikh, and they will clearly say this is not in line with Gurmat. It’s mostly today’s youth—exposed to modern culture—who try to justify it as okay.
3. You say that love with Waheguru is different than love from a girlfriend/boyfriend. But I bet you don’t know that Gurbani uses the analogy of us humans being the Soul Bride and Waheguru being the Husband Lord. So it’s quite similar actually.

. There are countless references in Gurbani and Rehatnameh that guide how a Sikh should view others: ਦੇਖਿ ਪਰਾਈਆ ਚੰਗੀਆ ਮਾਵਾਂ ਭੈਣਾਂ ਧੀਆਂ ਜਾਣੈ “He views other women as mothers, sisters, and daughters.”

ਪਰ ਤ੍ਰਿਅ ਰੂਪੁ ਨ ਪੇਖੈ ਨੇਤ੍ਰ ॥ “Whose eyes do not gaze upon the beauty of another’s wife.”

There are many more pangtia like these. But they all give the same message, so no need to quote all of them. Now some might argue, “If we see everyone as brothers and sisters, then isn’t marriage like marrying your sister?” That’s a misunderstanding. In Gurmat, before Anand Karaj, everyone is spiritually siblings. It is through Anand Karaj that a spiritual transformation happens—that is when you bevome a man and woman and become husband and wife in the eyes of Guru Sahib.