Madrid to Barcelona

Hello:

My boyfriend and I have finally decided to take a trip to Spain and we will be there from June 10th to June 22nd. We want to visit Madrid and Barcelona and also do some day trips to cities nearby. We want to travel from Madrid to Barcelona by train and thought it would be best to do it at night that way we can sleep and wake up in Barcelona. I went to the RENFE website but it won't allow me to purchase my tickets online. does anyone know of any website where I may be able to purchase the tickets for the overnight train in advance?
Thanks

RENFE only permits advanced booking within two months prior to the travel date. So just relax, and wait until April.

Have you considered flying to Barcelona? You can find easily tickets for 100€ round trip, and you can buy them in advance.

I have tried looking for a cheap airline and I tried booking with Vueling but they are only taking reservations till May. Iberia was too expensive and for Air Europa you are required to enter a passport number and I don't have that yet.
I will keep looking though. thank you for the suggestions.

A couple of years ago for work I had to fly to Barcelona twice a month. Back then I used to book a flight with Spanair, usually with only two weeks in advance, and I never paid more than 110€. I hope you find it. Good luck.