It doesn't matter if you're gay or straight watching them because movie love is pansexual. Gay people have been able to project themselves on to big screen hetero romances since time began (and eventually straight people will be able to do the reverse). My best guess in the difference of profound feeling is that Weekend is super-specific, inviting us into the intimacy, both sexually and conversationally like an invisible third lover while Like Crazy opts for shorthand and montage (like an entire summer shown in still flashcuts of the couple in bed) to signify "Falling in Love" rather than inviting us to do it in real time.
Of course to watch it now you may feel that Anton Yelchin is only this romantically tortured because he has to keep letting his other girl Jennifer Lawrence go. Her superstardom is just around the corner with Hunger Games (opening March 23rd). What horrible timing to lose her now!