Fibroadenoma is common in women around age of 30. It is usually benign and doesn't requires surgery always. Mostly it is due to hormonal imbalance but family history, use of some medications may also contribute. You requires regular manual breast examinations by your self for evaluations of size. Nothing to worry if size remains same or decrease but if its size gradually increases overtime this may lead to surgical interventions. There is no contraindications related to relationship as per your given history.