If you think he is self serving now.... marry him! It gets worse unless you snip it in the .... ummm..... bud!
If you love him and think he will change make him prove it.
If he ditches you at gathering now think of what will happen if you really need him.... will he come to your rescue or will he leave you stranded? And later brush it off as "get over it - its no big deal".
It may not be a big deal to him but it is to you. And your feeling and needs are just as important as his.