Nay.
Even if your relationship is rock solid, mixing finances is a great way to ruin it. Even the most understanding partner can become angry when they feel like they are being taken advantage of..and believe me, someone will eventually feel that way, even if it is not the case. No two people have the exact seem spending habits, but what is now a personal choice (what you/she spends her money on) will become a source of frustration, because every purchase will affect you both. So, nay.