Very important in husband wife relation.... thats all what I can say for now :@:
And its not about desi or walaithee.... every human is given a heart. Desi heart feels in same way as a walaithee does. Walaithee's probably would be contiminated but desi's are most of the time pure and innocent.
2ndly, its not haram between husband n wife but publically announcing it is surely something that crosses the ethical boundries ..... In Quran husband and wife are said to be each others Garments.
Kissing is haram between fiances too.. you can not until you are nikahfied.