Interesting subject and interesting questions.

On the contrary, I told my PD "if you have another boy friend, I will...."

I think your SP's behavior is abnormal, at least SP to PD level should say this think.  To be a good SP, she should know she is not the ONLY one.  Maybe she should be "sing le".

Agree with ching that we should never admit we have another unless that catch you on the bed.

If yr  SP really willing to give your $$, why not asking her to give you on regular basis, like x$ per month.  At least you can help her to save it and return to her when needed.

我终於想通解决方法: 偷偷芾SP去見LB,話佢知呢个係你條女,等LB未發現她在杀你前比SP杀咗,然后SP就比公安拉咗。哈哈,大哥你便可全身而退啦!