Any money that your partner puts into your account becomes your money, period. It no longer belongs to your partner. If that's not what you intend, you should keep your accounts separate.
Also note that any interest that is earned in your account belongs to you, and you have to report the interest income on your tax return and pay tax on it.
The situation might be different if you and your partner are married to each other and live in a community property state. But people do not usually refer to a spouse as a partner, so I assume you are not married unless you tell us otherwise.
