Insecurities suck. These are times that you are just too afraid to lose someone. When you realise that you would do everything for her.
But I've learnt something, you should keep your insecurities in. Because you also know, that person loves you unconditionally. Its just that there are also times when she is unable to provide the same to you, be she is occupied/sad/angry herself.
Someone once told me, Keep Your Ground, perserve, and you get over the obstacle. Quash insecurties.
Then, there are times where she would be insecure as well. Give her care, love, and warmth, even though she might not respond. But she knows in her heart, that you love her. Remind her that you are there for her, you'll catch her when she falls, you'll help her up when she trips, you'll soothe her temper.
Love is give and take, you give some, you get some. I've finally learnt that. =)