坐怀不乱难请拒绝他人坐怀投怀送抱难请接受他人投怀
[zuò huái bù luàn nán qĭng jù jué tā rén zuò huái tóu huái sòng bào nán qĭng jiē shòu tā rén tóu huái]
It expresses difficulties in both resisting and accepting others' advances towards you: On one hand it's tough to refuse others without appearing rude when their affections are unwelcome. And also hard to open up to affection even if the other person is genuinely interested.