Cannot Tell If Am In Love Or Not

I have a friend who is 27yrs old got married last year, but could not tell whether if she is actually in love or not. she dated the guy for five years no quarel, no arguement, accepted  him but can not tell if she actually loves him. Any time we are together she will be asking me, how to know when somebody is in love. I have tried my best but she is still comfused. ur oppinion please. 

I would say the fact that she is asking is a clear indication that she is NOT in love.
When you are in love you know! It may not be the right person but you know that you love them.If it is the right person and they love you back there is nothing better in the whole world!
It is like having a child.That love comes naturally (for most),but it is just strong feelings of wanting to give and be close to and share.
When you look at the person you love you want to do all you can to make them happy.In fact just looking at them gives you joy.
When you are in love there are still times of stress and arguments with your other half, but you overcome them together with give and take.
I hope she comes to her own conclusions in time.