1. But that has judgmental overtones, so I'll hold that in reserve.
但這個(gè)帶有批評(píng)色彩，還是作為備用吧。

備用

e.g: We always keep some money in reserve, just in case.
我們總是存些錢(qián)備用，以防萬(wàn)一。

2. Next to you, I'll look like a catch.
?
有你在旁邊，我更有把握了。

a (good) catch
可托付終身的好人（幽默）

3. I'll have to have you over for spaghetti some night.
我改天晚上叫你過(guò)來(lái)吃。

have sb. over
請(qǐng)某人到家里來(lái)吃飯

e.g: We must have you over for dinner before we leave.
在我們走之前一定要請(qǐng)你到家里搓一頓。

4. You can't hang out with your roommate's ex.
你不能和室友的前任一起玩。

與...出去完；與...閑逛

e.g: I don't really know who she hangs out with.
我真不知道她和誰(shuí)在一起玩。