Best practise how to sync SQL Server 2014 database with other database
It sounds like what you are looking for is an Always On Availability Group in Synchronous Commit mode with automatic failover.  The transactions sync from the primary to the secondary and in the event of a system failure, will pass ownership of the database to the secondary. Your application would need to be aware of both the primary and secondary and which one is active.  This feature does make use of the cluster service but you don't have to have an actual cluster with shared storage (see this post from Brent Ozar for more details about hot to work around that). This is the more expensive option, since it requires Windows Enterprise.  

You can implement mirroring in high safety mode which does essentially the same thing on any edition of windows, even a desktop if you want, since it doesn't require clustering features. You won't get all the extra benefits, but if you just want to have a synchronous hot standby of your database then it will do that. The caveat here is that mirroring is deprecated, so if you implement this now, you will eventually have to migrate to availability groups in the future.