Throwing a housewarming party, or a wedding, is not that hard at the core of it. You invite friends and family, maybe some neighbors, maybe your real estate agent, and then a few people who you don't expect to show up. You organize some snacks and a selection of drinks, coordinate some musical entertainment, and the party handles itself as long as people actually show up. Typically, there is some gift-giving, unless you are in the habit of throwing these sorts of parties less than once a year. The typical gift is some sort of useful home tool or accent. You know the crap of which I write, candles, towels, big spoons, breadmakers, wall hangings, etc.
These gifts are all supposed to help you make the place a home. Your friends have given you these things to ease your transition from one space to another, and in the case of a wedding, from one lifestyle to another. There you were, with those things that were yours, and here you are, with these things that are the happy couple's. You don't need to worry about how you will grate your cheese from now on, but you will worry about who will shower first. You can focus on the two of you, now that you have an automatic coffee maker. You can throw away that towel that other women or men have used, but you can not throw out those memories. You have the time to talk while the slow-cooker makes dinner for the next few nights. You have an unsafe number of scented candles gathering dust on your bookshelf, but now you need to buy a new bookshelf because that one doesn't quite fit the style you're aiming for in this room. You buy furniture with a style, formerly second to purpose.
Somewhere in all this, the relationship will fall into place. These gifts will aide you in merging two lives into one. All fear for the future will be eased matching flatware and silver. All doubts will disappear as the home becomes a comfortable place. All desire will dissipate under the relentless wheel of routine.