Fear prevents you from committing to the person you care about the most. You worry that your heart will be shattered.
You don't want to do anything to harm the friendship. You worry that the two of you will eventually grow apart, and that nothing will ever be the same between you.
They may not share your feelings, and that makes you nervous. You worry that your interpretation of their signals has been off.
You worry that becoming buddies will make you less effective. You worry that it wouldn't seem proper to kiss them.
If they know you even a little bit, they can easily say no. They are well aware of your faults and undesirable tendencies.
That your emotions may overwhelm theirs is a major worry. You worry that they will agree to a date with you only to avoid upsetting you.
You're too nervous to take a chance and ask them out on a date. Fear that the date won't go as smoothly in reality makes you nervous.
You're worried that you've begun to conflate platonic companionship with good desire. You worry that hanging out with them might be a mistake.
You worry that they will treat you like a sibling. You worry that they have no desire to continue the relationship with you.
You worry that you're developing unhealthy feelings for them. You worry that you wouldn't be able to cope with their loss.
You worry that they haven't moved on from their previous relationship. Your insecurity stems from the fact that you know you won't be able to hold your own.
You worry that you may accidentally damage them. You're worried that your words may hurt them deeply.