I believe Love is in levels. The more you know a person, the more you can love the person. If for instance, you meet a stranger for the first time, you are most likely going to be neutral towards him. But if you get a call from your mum saying that person is your cousin, you immediately feel an attraction towards the person. This shows that love is dependent on relationship.
Having said this, on the issue of love conquering all, it depends on what “all” has up their sleeve on any given day. Love is dependent on the two people involved in the relationship.
So depending on how much they love themselves, sometimes love wins. Sometimes 'All' does. So the answer is under the right circumstances.