Rather I think the love of a friend is much stronger than the love of a lover...

I have to disagree here. A friend's love is limited compared to the love of a partner.

There's quite a lot of similarities though, but there's no love more selfless than that of a partner. A partner will always go the extra mile, a partner will always get unnecessarily jealous, a partner will always get mad yet fall deeper in love, it's a spell-like shit, it gets one at it's mercy. You can't really compare the love that flows through partners, it's sacred and more powerful.