你的句子没有问题，see 在此表示“见面”“约会”“谈恋爱”等，可以用于进行时态，也可以连用时间段状语：
They'd been seeing each other on the sly for months. 他们已经偷偷约会了好几个月。
They’ve been seeing each other on and off since Christmas. 圣诞节过后，他们隔二差五地见面。
They’ve been seeing each other for over a year. 他们恋爱一年多了。
Since the separation they've each been seeing different people. 自从分居以后，他们都在和别人交往。
They say her husband's been seeing that Mrs Hastings again. 听说她丈夫又跟那个黑斯廷斯夫人有来往了。
