Why do guys keep giving up on me/not want a serious relationship?

Hi,
So i've talked to about 3 guys now this year and it only lasts about 2 weeks at most with each. We get on really well both like each other but then when it comes to putting in the effort/when i say i want something really serious (a full on relationship) they all back out even though they tell me they wanted that as well.
1 of the guys. we had all the same views/morals/opinions and when i asked him to spend more time chatting with me because he would only speak to me 2hrs a day at most, he said he cant have a relationship its too much right now and bailed out.
Why do guys not actually want a serious relationship?
Have I just not met the right guy or am i the problematic one? am i expecting to much?
Thank you

How old are you?

A full relationship after only knowing someone for two weeks is quite a big ask. It probably seems like you're jumping too quickly to a relationship or rushing things, why not ask to go on a date or wait until you've known each other for a fair bit of time?