Some things I've found between my own writing and books... not sure how good they are in retrospect (aroace) buuuut... maybe it can help because I'm in a writing rut and haven't been able to use much of them (if anything, at least read the end paragraph)
*Love being described as a yearning so intense the protag felt their heart thumping so hard and head going so light that they felt they might pass out if they didn't get the love intersst
*A forbidden/unreciprocrated love making the protag's blood drain from their face and lungs tighten at the mere sight of the love interest
*Love being felt as pure and unadulterated, painful need. The protag seeing the love interest in another room and feeling their hands clench aimlessly around air in need of feeling the love interests skin, inhaling cold air and begging for the warm air of the other's breath, blood draining to the protag's legs when they see the love interest doing something amazing.
*Love feeling like skin burns every time the protag thinks of the love interest, feeling their muscles tense in anticipation of the affection even without actively receiving it, feeling their diaphragm raise and keeping them from breathing normally because the body is so used to gasping, panting breaths around the love interest.
*Love feeling like the protag is being ripped out of their own skin when they're away because they aren't feeling the familiar contact of their love interest. The ache in the protag's arms like they need to stretch or pop their limbs that only gets soothed by the firm hug or cuddles of their love interest.
*Love described accurately as *hell*. Burning, aching hell. Unable to stop thinking about them but more specifically unable to stop the feeling of the protag's stomach dropping the moment they realize they can't stop thinking about them. The dread that comes with falling in love so innately that the protag realizes the physical manifestations actually exist.
*The quiet love being felt only in the protag's mind. The subtle thoughts of "That's my person" when the love interest barely does a thinf and the feeling of fullness in their lungs because they Said that and they Meant that.
*The loud love where the protag actually hisses and growls in their room because that's the only way they can get that aggressive love out. They love the love interest so deeply and intensely they can feel the burning hot sensation taking control of their limbs like their blood pressure has suddenly tanked and the only way to get it out is to hiss and grow while clutching their chest as it tightens with heat
*The protag walking into the room and seeing their love interest minding their business and their shoulders instinctively relaxing as they smile
*The touched starved love of the protag's skin burning and burning until the other's skin is touching theirs, their minds becoming so overwhelmed that they can't think of anything until they can feel the touch to ease the genuine burn in their skin
The only real definition and distinction between familial love and romantic love and platonic love is... the individual themself. All of those can be applicable to any relationship, and I think that's amazing.
If you wanna write good romance, think of how you feel about seeing your friends, and call it romance. It's the *intent* that makes it difference. The *intent* is what differentiates romance from platonic or familial.
Have fun with it. Make romance casual. Make romance intense. Make it calm. Make it angry. Make it ache. Make it burn. Make it smooth. Make it easy. Subtle. Blatant.
Love is love. We say that for so many things but really... the only thing that separates the different genres of love is personal intent.