Don't you always wonder why relationships are fun in the beginning

Don't you always wonder why relationships are fun in the beginning & then it feels like something isn't there anymore later on? It's because someone stopped doing what they did to get you & now that you're theirs, they feel like they don't have to try as hard, they feel like they don't have to do as much. Before, they used to pay attention to you, text you all the time, reply back quick, be on the phone for hours, have so much to say, always doing this & that for you when you don't even ask them to, be all over you & now, they keep their hands to themselves, they ran out of things to talk about, conversations go dead, not making you feel like you're wanted by them. & that's when you guys start drifting.