It's nice to do something special for your spouse on certain significant days.
It's better to be consistent in honouring God every day in your relationship.
Both are great, but if you were only to do one, be sure to do the harder thing and be in it for the long haul.
If you are looking for ideas for Valentines day, consider whether your spouse has a particular love language and start there. But again, if you are not being consistent, it is better to start reforming your relationship by learning to serve your spouse in a biblical way.