Nothing is apart from God, and this perfect non-separation is seen as a form of 'intimacy' with the divine. It's not that YOU specifically are loved; it's that you are not, and you cannot be, apart from infinity. The divine is the total condition of all being, and to be "loved" more precisely means to be absolutely held and absolutely known, which you always are, as per the nature of divine omnipotence.
What they essentially wanted to say with this back then but summarized as 'attachment'/'love' is that there is never any privacy from God, and no escape or rejection of it is possible even if you think it is, because being part of everything, it is always with you. This is what it means to know that you will never be alone; and that is technically a form of 'love', isn't it? It is God that torments you, and God that pleases you.
Of course, the idea of that is horrifying to a typical human, which is why priests and preachers skirted around it extremely hard when imparting gospel to the masses. Mystics revealed these ideas and then passed it to priests, who were charged with the task of taking the complex and confusing ideas of the mystics and boiling it down into understandable terms for commoners (this was especially hard because philosophy was often written in Greek, and the regional lingua franca, Aramaic, simply did not have any terms that conveyed the ideas which could be communicated in Greek). So, they did what they could with the most commonly understood and closely analogous words of the time. Attachment became love. No one would want to convert if you opened with: "GOD IS THE EMBODIMENT OF EVERYTHING, AND YOU ARE HELPLESS TO RESIST!".
Anyway... All of this is a big part of why, mostly in early mystic texts, there was a big theme around cosmic ecstasy and bliss being ego-dissolving. They actually came up with a term for this a lot later on in Jewish Kabbalah; it's a concept called 'Devekut', which roughly refers to being cleaved, or merged. This 'love' is your ego death, the unity of your soul with the divine to create something new and qualitatively better as you merge closer and closer to this source of unity (God).