Well, they usually fall on the floor and start playing air guitar while using their feet to turn themselves in circles. Of course, that's just the average guy. Your friend might be different.
Every guy is different. For example: my boyfriend decided that the best way to get me was to trick me into a first date and convince everyone I was his sister. Somehow it worked?
My boyfriend and I have always said we weren't the marrying type. We still aren't, to an extent. But the moment I realized he loved me was when he said that I made him feel like being domestic. Sweet in his own way, I suppose. Besides that, I think time is the biggest factor. If you've been dating for a short amount of time and he comes out early with declarations of love, most likely he's just wrapped up in passion. That is, if you don't believe in love in first sight, which I don't. PB