To separate romantic love from other forms of love, the most obvious answer is that romantic love is rivalrous and excludable. The more you have for one, the less you have for another.
Unlike friendship, romantic love cannot be shared, as it is an relationship strictly for two (or certain number, if u like open relationships). To form this relationship, you must deliberately create secrets to bond you two and exclude the others. Friendship circles might exhibit a similar behavior, but it can most certainly expand, unlike romantic ties that's exclusively for two. To be very strict, having a romantic relationship with another means that you must be willing to give up your world for one person--and thus true love is rare in real life.
But don't get me wrong; other forms of relationship, like friendship or just your average marriage-level love, is also good--in fact, those welcoming, easy relationships are far more practical and beneficial.
And this leads to my final point: the impracticality of romance is not its flaw, but rather its defining feature. Being impractical and damaging, the act of falling in love becomes an art, it raises it above the mundane, pragmatic desires.
Like a useless piece of glamorous luxury, love is to be admired but not always desired.